Preheat the oven to 350F. Line a muffin pan with muffin liners--I don't recommend oiling the pan for this recipe. Stick with the muffin pan liners.
Combine the ingredients, except chocolate chips, in a high-powered blender jar or food processor bowl.
Pulse until the batter is smooth, scraping the sides if necessary.
If using, stir in the chocolate chips.
Divide evenly into 12 muffin cups.
Bake for about 18 minutes, or until golden brown and spring back when lightly touched.
Notes
*Helen perfected this recipe and used Costco almond butter which is fairly runny. I've made these muffins a lot since she perfected the recipe and have used both the Costco almond butter and the creamy almond butter from Whole Foods (just almonds on the ingredient list). If there's a lot of oil at the top of your almond butter jar, thoroughly stir the butter to incorporate the butter with the oil before using in this recipe. Stick with using a creamy almond butter with very minimal ingredients (preferably just almonds). If you don't want to use almond butter, any natural nut butter should work if it’s the right texture. For a nut-free option, sunbutter will work, but it does turn the muffins green when baked. This doesn't change the taste of the muffins, it's just a chemical reaction with the baking powder.