Brown Butter Oatmeal Muffins

Mix together milk and vinegar in a large bowl. Stir in oats and allow mixture to soak for at least 15 minutes.

Meanwhile, prepare brown butter. Add butter to a small, light-colored saucepan over medium heat. Cook, swirling pan constantly, until butter is melted and brown bits begin to form on the bottom of the pan, 7 to 10 minutes. Remove from heat and allow to cool slightly.

Preheat the oven to 375 degrees F (190 degrees C). Grease a 12-cup muffin tin or line cups with paper liners.

Stir flour, baking powder, baking soda, salt, cinnamon, and nutmeg together in a bowl. Set aside.

Add cooled browned butter, maple syrup, and vanilla to the soaked oats. Whisk until combined. Add in egg and mix until thoroughly combined. Mix in 1/2 of the flour mixture and stir until just combined. Mix in remaining flour mixture, stirring until just combined. Fold in raisins and walnuts.

Spoon batter into the prepared muffin cups, filling each 3/4 full.

Bake in the preheated oven until tops spring back when lightly pressed, 15 to 18 minutes. Cool in the tin for 5 minutes. Transfer to a wire rack to cool completely.