Preheat Oven: Preheat your oven to 170ºC (340ºF). Line a 12-hole muffin tin with paper cups; set aside.
Melt Butter: Melt the butter and set aside to cool slightly.
Combine Dry Ingredients: In a large mixing bowl, sift together the flour, baking powder, and baking soda. Whisk in the sugar.
Add Wet Ingredients: Pour in the applesauce, beaten egg, melted butter, and vanilla. Fold and mix with a rubber spatula until just incorporated, taking care not to over-mix.
Incorporate Chocolate: Fold the chopped chocolate through the batter until just combined.
Fill Muffin Tin: Spoon the batter into the muffin cups, filling each 3/4 full. Use a small cookie scoop for even portions, placing 2 scoops into each cup.
Bake: Bake for 18-20 minutes, or until the muffins are lightly golden and a toothpick inserted into the center comes out clean.
Cool: Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely. Serve and enjoy!
Notes
Store: In an airtight container at room temperature for 3-4 days.
Freezing: Wrap muffins individually in plastic wrap and then place them in a freezer bag. Freeze for up to 3 months. Thaw at room temperature or microwave for a few seconds before serving.