Using a tablespoon or small cookie scoop that's been sprayed with cooking spray (helps batter slide off spoon or scoop easily), form rounded 1 tablespoon mounds and place mounds into prepared pans. Each cavity should be filled to a solid 3/4 full.
Allow muffins to cool in pans for about 10 minutes, or until they've firmed up and are cool enough to handle. Muffins are best fresh, but will keep airtight at room temperature for up to 5 days, or in the freezer for up to 4 months.
Adapted from Averie Cooks. You can not omit the peanut butter in this recipe, so if you have nut allergies or detest peanut butter this recipe is not for you. These make for very rich tasting muffins.