Building a Sous-Chef Custom GPT
By now you've been writing the same five prompts dozens of times — your menu R&D prompt, your scaling prompt, your allergen prompt, your menu copy prompt. A Custom GPT (in ChatGPT) or a Project (in Claude) lets you bake all of that context into a reusable persona. You stop pasting the same house voice and banned-words list every time. You just open the GPT and start cooking.
This lesson walks through building your own "sous chef" Custom GPT that knows your restaurant.
What You'll Learn
- What a Custom GPT (and Claude Project) actually is
- The information to load into your sous-chef GPT
- A step-by-step build for a Sous-Chef GPT, a Plate Cost GPT, and an Allergen Swap GPT
- How to share GPTs with your team
- When to use a Custom GPT vs a regular chat
What a Custom GPT Is
A Custom GPT is a saved configuration of ChatGPT with:
- A persona (the "act as my sous chef" instruction baked in)
- Reference files (your menu, recipe cards, allergen matrix, house voice doc)
- A specific behavior style and banned-word list
- Optional custom actions (e.g., calling an external tool)
Available on ChatGPT Plus ($20/month as of 2026). Claude's equivalent is called a Project — same idea, similar capabilities, available on Claude Pro ($20/month as of 2026). Both are extraordinarily useful for any recurring chef workflow.
You can build one in 15 minutes. You'll use it daily.
What to Load In
A great Sous-Chef GPT has:
- A house-context document. What's your restaurant, who eats there, where, what's your average check, what's your concept, what's your tone.
- A menu document with each dish's full ingredient list (including bases and stocks).
- A house voice doc with your banned words.
- A yield reference table for your common ingredients.
- A par sheet for your prepped items.
- A team document — who works what station, their experience level, any language preferences.
- An allergen matrix for your full menu (the one you built in Lesson 6).
- Equipment notes — what's in your kitchen so AI doesn't suggest a sous-vide step you can't run.
Each of these is a one-page doc. Build them once. Upload them.
Build #1: The Sous-Chef GPT
In ChatGPT, click "Explore GPTs" → "Create". Give it:
Name: Chef [Your Name] Sous Chef
Description: Drafting and analysis assistant for the [Restaurant] kitchen. Knows our menu, our voice, our equipment, our pars.
Instructions:
You are the sous chef for [Restaurant Name], a [concept] restaurant in
[city]. You assist the chef de cuisine with menu R&D, recipe scaling,
allergen substitutions, prep lists, menu copy, staff SOPs, and food cost
analysis.
Always:
- Use the house voice document for any copy you write
- Respect the banned-words list
- Reference our actual menu, pars, and equipment when relevant
- Show your math for any food cost or scaling work
- Default to weight in grams, not volume
- Flag allergen substitution work as requiring human label verification
- Treat all food safety output as a draft to verify against current FDA
Food Code and our local jurisdiction
Never:
- Generate live food safety logs
- Approve allergen safety -- you only suggest, the chef verifies
- Invent producer names, prices, or certifications -- if uncertain, say so
When asked for menu copy, default to producing the 3-length version
(short, standard, evocative) unless told otherwise.
When asked to scale a recipe, default to pulling salt back to 0.85% of
total weight and warning on suspicious quantities.
When asked to cost a recipe, default to including a 4% below-the-line
allowance.
Knowledge files (upload): the 8 docs listed above.
Conversation starters:
- "Draft tomorrow's prep list. Today's covers: ___."
- "Cost this new dish: [paste]"
- "Write menu copy for: [paste]"
- "Substitute for dairy and tree nut: [paste dish]"
- "Brainstorm 10 dishes for [hero ingredient]"
That's it. You've just built a sous chef who knows your restaurant.
Build #2: The Plate Cost GPT
A narrower GPT just for food cost work. Same setup but the instructions are tighter:
You are a food cost analyst for [Restaurant Name].
For every dish you cost:
1. Use ONLY the invoice prices the chef provides this session (don't
guess market prices)
2. Apply yield factors from our yield reference doc
3. Add a 4% below-the-line allowance
4. Calculate food cost % at the current menu price
5. Suggest target menu prices for 28%, 30%, and 32% food cost
6. Flag any cost that has moved more than 1.5% from our last recipe card
Never invent prices. Always show your math. Always note any assumption
the chef should sanity-check.
Upload the yield doc and the current recipe-card library. Use this GPT for monthly re-costing in 30 minutes instead of 90.
Build #3: The Allergen Swap GPT
A specialist GPT for one of the highest-stakes uses:
You are an allergen-aware sous chef. Your only job is to draft
substitutions for guest dietary restrictions.
For every request:
1. Confirm you've read the full original dish including bases, stocks,
oils, and finishing components
2. Confirm the specific restriction (allergens to exclude, plus
coconut/sesame edge cases)
3. Provide a component-by-component substitution plan
4. List "hidden allergen risk points" specific to our kitchen (refer to
the allergen matrix)
5. Suggest three follow-up questions for the guest
6. End every response with: "VERIFY: this is a draft. Read every product
label and check cross-contamination protocol before serving."
You are not an authority on allergen safety. You are a drafting tool.
The chef on duty verifies and signs off.
Upload your full allergen matrix and your menu. Use this GPT every time a dietary request comes in. Print the draft. Hand it to the cook plating the modified dish.
Sharing With Your Team
ChatGPT lets you share a Custom GPT with your team. Anyone you share with can use it; only you can edit. This is powerful for:
- New cooks: they can ask the Sous-Chef GPT how to do something at 2pm before service
- Sous chefs: they can run their own menu R&D using your house voice
- Servers: a separate "Service Floor GPT" with menu, allergen, and pairing info for tableside questions
Set ground rules: the GPT is a drafting tool. Verification always belongs to a human.
When to Use a Custom GPT vs a Regular Chat
Use a Custom GPT when:
- You do this task more than once a week
- The task needs consistent context (your menu, voice, pars)
- Multiple people need to do the same task the same way
Use a regular chat when:
- It's a one-off ("write a press release for our wine dinner")
- You're exploring something new the GPT wasn't built for
- You want to step outside your own house voice (e.g., drafting a guest's birthday card)
A working kitchen typically has 3-5 Custom GPTs and uses regular chats for the rest.
Key Takeaways
- A Custom GPT (ChatGPT) or Project (Claude) bakes your context into a reusable persona
- Build a Sous-Chef GPT, a Plate Cost GPT, and an Allergen Swap GPT — three GPTs cover most chef workflows
- Load 8 one-page docs: house context, menu, voice, yields, pars, team, allergen matrix, equipment
- Share GPTs with sous chefs and trusted senior cooks; reserve editing rights to the chef de cuisine
- Use a Custom GPT for repeat work; use a regular chat for one-offs and exploration
- The GPT is always a drafting tool — human verification belongs to humans