Preheat oven to 350 degrees F. Line an 8 x 8-inch pan with parchment paper, leaving a 2-inch overhang on two sides.
Add the mashed potatoes, eggs, honey, butter, and vanilla to a medium bowl. Whisk well to combine into a smooth mixture.
Add the flour, cocoa powder, baking powder, salt, and chocolate chips. Stir in to combine fully.
Pour batter into the prepared pan and smooth evenly with a spatula.
Bake for 28-30 minutes or until the center is set.
Remove from the oven and let cool fully in the pan before slicing.
Notes
Store brownies at room temperature or the fridge in an airtight container for up to 5 days.
If using homemade mashed sweet potato, plan to make it ahead so it has plenty of time to cool down.
Dairy-free: Use dairy-free chocolate chips.
Gluten-free: Use certified gluten-free oat flour. (You'll want to use 2/3 cup.)
Because these brownies are so wonderfully fudgy, you want to make sure they cool fully before slicing, and it's actually easiest to slice them after they chill a little bit. When you’re ready, use the parchment paper to lift the entire bar out of the pan and place onto a cutting board to slice.