Preheat the oven to 400℉. Line muffin tins with 16 paper liners and set aside.
In a medium bowl, mix together the all purpose and almond flours, baking powder, baking soda and salt.
In a large bowl, mix together the sugar and orange zest until fully combined. Mix in the orange juice, eggs, vanilla, butter and sour cream.
Slowly mix the dry ingredients into the wet ingredients until just combined. Fold in the chocolate chips.
Divide the batter evenly into the prepared muffin tins and bake in the preheated oven for 15-18 minutes, or until a toothpick inserted into the center comes out clean.
Notes
Do not overmix the batter! A few lumps is perfectly fine, and will actually produce softer and fluffier muffins.
When zesting the orange, avoid the white pith as that can cause the muffins to be more bitter.
Storage: You can store the muffins in an airtight container at room temperature for up to 3 days.
Freezing: You can freeze these muffins for up to 3 months. When freezing, place cooled muffins in a freezer bag and try to remove as much air as possible. When you are ready to eat them, thaw at room temperature or microwave for 20-30 seconds before serving.
These muffins are especially delicious served slightly warm, when the chocolate chips are soft and melty.