Preheat oven to 425°F and line the muffin tins with squares of parchment paper or liners
Mix together the all purpose flour, cocoa powder, baking soda, and salt. Set aside
In a medium bowl, whisk together the egg, Greek yogurt, oil, and milk. Whisk in the granulated sugar
Use a spatula to fold the dry ingredients into the wet. The batter will be fairly thick. Mix in the chocolate chunks. I like to set aside ~30 chunks to sprinkle on top of the muffins before baking
Spoon the batter into the prepared muffin tin. Add a few chocolate chunks on top of each muffin
Place in the middle rack of the oven and bake for 5 minutes at 425°F. Reduce the oven temperature to 350°F and bake for another 15 - 16 minutes until a toothpick comes out free of batter. Melted chocolate on the toothpick is okay
Remove from oven and let cool for a few minutes. Use a butter knife or spoon handle to gently poke a hole in the middle of each muffin. Fill with chocolate hazelnut spread and enjoy🫶
