Preheat the oven to 375°F. Line a muffin tin with paper liners or lightly grease with non-stick spray.
In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, whisk together the milk, vegetable oil, egg, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; it's okay if the batter is slightly lumpy.
Gently fold in the Gingerbread Butter, creating swirls in the batter. Do not fully incorporate the butter; you want to see swirls in the finished muffins.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Bake for 15-20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.
