Preheat your oven to 400 degrees and line a muffin pan with liners. Set aside.
Sift flour, sugar, baking powder, and salt into a large bowl.
In another large bowl (or use your stand mixer), beat the softened cream cheese until creamy.
Add in the eggs and beat until smooth.
Add in the milk, vanilla, and melted butter and mix thoroughly.
Pour the cream cheese mixture into the flour mixture bowl. Use a large (wooden) spoon to mix until fully combined.
Add in the chocolate chips and peanut butter chips and stir to make sure they're evenly distributed.
Use a large cookie scoop, or ice cream scoop, to distribute the batter evenly amongst the 12 muffin wells.
Generously (I should have been more generous), sprinkle the tops with the chocolate sanding sugar (or turbinado sugar).
Bake for 20-25 minutes or until the muffins just start to brown and are slightly firm.
Let cool then enjoy!