Prep the Chicken: Cut the chicken into bite-size pieces. Let me be honest here, you can skip this step if you want. The only reason I do this is because traditionally butter chicken is cut. If you prefer cooking whole pieces of chicken and cutting them as you eat, go for it. 

Make the Marinade: Stir together the 2 teaspoons olive oil and curry powder. This ensures that the chicken gets evenly coated with the curry powder. If you just plop the curry in, sometimes some pieces get a lot of curry while others don’t get much at all. 

Place the chicken in a medium bowl. Add the curry-oil mixture. Stir together to coat. 

Note: You can do this right before you cook dinner or up to 24 hours in advance. If prepping the night before, cover the bowl and refrigerate. 

Slice the Onion and Cook: Cut the onion in half from stem to tip. Then cut into thin slices. Heat one teaspoon olive oil in a nonstick skillet until it shimmers but doesn't smoke. 

Add the onion. Cook, stirring frequently, until soft. Add the sauce. Reduce heat to low and allow sauce to simmer while you cook the chicken. If the sauce seems too thick, add a splash (1/4 cup) water.

Cook the Chicken: Heat remaining olive oil in a large nonstick frying pan.

For cut chicken: Add the chicken, cook, stirring frequently, until no pink spots remain, about 5 minutes. 

For whole boneless thighs or breasts: Place chicken into hot pan. Cook for three minutes. Turn. Cook until chicken is no longer pink in the center. Cooking time varies depending on the thickness of the chicken. 

Put it Together: Add the half and half to the sauce. Stir to combine. Pour the sauce over the chicken. Stir to combine. Reduce heat to low. Allow chicken to simmer for about three minutes. Chicken should reach 165 degrees F. 

Transfer to a serving platter. Sprinkle cilantro over the chicken, if desired.