In a small bowl or ramekin, combine salt, black pepper, and garlic powder. Sprinkle seasoning on both sides of all 4 chicken cutlets.
Add flour to a shallow bowl. Dip and dredge the chicken in the flour so both sides are coated.
Heat a large skillet over medium-high heat. Add olive oil and 1 tablespoon of butter.
When butter has melted, add the chicken cutlets and cook for 4-5 minutes per side, or until golden brown. Transfer the cutlets to a plate and set aside.
Add the remaining 1 tablespoon of butter, garlic, and onions to the pan. Saute for 3 minutes, until onions have softened.
Reduce the heat to medium and add the minced chipotle peppers in adobo sauce, heavy cream, and milk. Whisk together to combine and bring to a gentle simmer.
Add the browned chicken cutlets back to the pan and cook for 5 more minutes, until the sauce has thickened and the chicken is cooked through.
Garnish with chopped cilantro and serve.
Notes
Storing and reheating: Leftovers keep in an airtight container in the fridge for 3 to 4 days. Reheat low and slow in a skillet over low heat or in the microwave in short bursts, stirring in between. High heat will split the sauce. I don't recommend freezing this one, since cream sauces tend to break when thawed.
Heat level: 3 chipotles lands on the mild side once the cream goes in. Use 1 or 2 for milder, 4+ for spicier. If you want more smoke without more heat, add a spoonful of the adobo sauce instead of another pepper.
Doneness: The chicken is done at 165ºF in the thickest part. Since it finishes in the sauce for the last five minutes, pull it from the first sear while it's still shy of that.
Swaps: A gluten-free 1-to-1 flour blend works for the dredge. Half and half can replace the heavy cream for a lighter sauce that won't thicken quite as much. Shrimp or pork cutlets work in place of chicken, and shrimp only needs a couple of minutes at the very end.
Any boneless, skinless chicken cut works here, including thighs. Just give thighs a few extra minutes.