Wash spinach and chop if it is mature-leaf spinach (“baby spinach” can be used whole). Mince garlic cloves and set aside.
Make sure that your chicken breasts are fairly uniform size and thickness. If not, pound the thicker parts to make thinner. You want the chicken to cook as evenly as possible.
Dice squash into 1” cubes. Place on a pan (preferably with a Silpat cooking sheet so you don’t have to use more oil) and toss in 1 tbsp. butter and rosemary.
If you are using any fresh herbs, mince them before mixing together with the remaining 1 tbsp. of butter.
Rub the herb mix on the chicken breasts and then place them on the pan with the squash.
Bake the chicken and squash for about 35-40 minutes or until the thickest part of the chicken has an internal temperature of 165°.
After baking, let the chicken rest for at least 5 minutes before slicing.
The spinach only takes a few minutes to prepare, so you can do so while the chicken is resting.
Melt butter in a skillet over medium high heat.
Heat garlic in the butter for 1 minute. The butter and garlic together should smell heavenly.
Add in spinach handful by handful. It will cook down quickly and turn a bright green color.