Pre-heat oven to 350 degrees. Arrange 7 jumbo silicone baking cups on a small baking sheet. Set aside.
Mix dry ingredients, then add wet ingredients and mix until just combined. Divide mixture evenly into silicone baking cups.
Bake at 350 degrees for 10 minutes. Add walnuts on top, if desired. Continue baking for an additional 12-15 minutes or until a toothpick inserted into the center of a muffin comes out clean.
I recommend using these silicone baking cups!