Stuffed Chicken Breast with Mozzarella and Spinach

Adapted from Christina Cherrier. Source nutrition is reported only where its per-portion basis is supported. Unavailable totals are not estimated.

Before cooking

The publisher lists 886 calories without a serving size or complete nutrition breakdown; per-portion nutrition remains unreported.
Source crushed-tomato can size is unspecified; this adaptation retains one can and requires checking its size before shopping. Sugar is present in the source and retained, despite roundup keto framing.
The publisher does not specify the size of at least one can or bag. Check the intended package size before shopping.
Ingredient quantities are scaled from 2 original portions to four portions. Fractions of whole items may need weighing or dividing after preparation. Larger batches need extra cooking space or batches; keep thickness and endpoint checks.
Adapted from Christina Cherrier. This adaptation has not been kitchen-tested.
The source does not provide verified values for every per-portion macronutrient. Missing values stay unreported; a keto label from the publisher is not a verified net-carb total.
Safe doneness checks are added to the publisher method; timers alone do not establish doneness.

Source can size is unspecified; confirm before shopping. Sauce and chicken can cook in parallel in two skillets.
Check poultry or reheated cooked chicken reaches 165°F at the thickest center.
2 count small onionminced	For sauce: one-third oil, onion/half garlic 3–4 min, tomato/stock 15–20 min, then sugar/balsamic/seasoning; reserve.	Pour sauce around cooked stuffed chicken and simmer briefly.
2 can low-sodium crushed tomatoes
2 tbsp sugar
1 tsp balsamic vinegar
1 cup chicken stock(125ml) is the source parenthetical; original US quantity controls.
2 tbsp olive oildivided
4 count garlicminced
4 count boneless skinless chicken breastsbutterflied	For stuffing: another third oil and remaining garlic 1–2 min, wilt spinach 2–3 min. Butterfly chicken, stuff with spinach and mozzarella, season/fold; cook in last third oil 5 min/side to 165°F.
4 tbsp olive oildivided
4 slice fresh mozzarella cheese
4 cup fresh baby spinach
4 count garlicminced
to taste Crushed red pepper flakesto taste (optional) · Unquantified in source; use to taste or as optional garnish as stated. Optional; excluded or included as stated in the publisher nutrition.
to taste Salt and fresh cracked pepperUnquantified in source; use to taste or as optional garnish as stated.

Step 1. For sauce, use one-third of the oil to soften onion and half the garlic for 3–4 minutes. Add crushed tomatoes and stock; simmer 15–20 minutes. Stir in sugar and balsamic, season and reserve.
Step 2. In a second skillet, use another third of the oil with remaining garlic for 1–2 minutes. Wilt spinach for 2–3 minutes and reserve.
Step 3. Butterfly and season chicken. Fill each breast with mozzarella and spinach, then fold closed and add optional flakes.
Step 4. Heat remaining oil over medium heat. Cook stuffed breasts about 5 minutes per side, continuing until the thickest chicken and filling reach 165°F. Add sauce around chicken and bring back to a simmer.