Chop chicken breasts into bite-size pieces
Place flour and cayenne pepper in a large ziplock bag and shake to mix
Add chicken to bag and shake to evenly coat all pieces
Remove chicken from bag and shake off any excess flour
Heat olive oil in a large skillet over medium heat
Add chicken to pan and cook until all pieces are beginning to brown to a light, golden color about 5-7 minutes
Remove chicken from pan and cover to keep warm
Add butter and mushrooms to the skillet and cook until mushrooms are nicely golden, about 5-7 minutes
Add chicken, chicken broth, cream and pesto to pan and stir to combine.
Cook for a few minutes more until sauce has started to thicken.
Season with salt and pepper, to taste
Top with freshly grated parmesan, if desired