Pineapple blueberry muffins are one of my favorite make-ahead breakfasts. These homemade muffins are filled with fresh, juicy blueberries and tangy pineapple!
Preheat oven to 400°F (200°C). Line 12 standard muffin cups with paper liners, or grease the muffin cups if you want to skip the liners.
Whisk together the flour, sugar, brown sugar, baking powder, baking soda, and salt in a large bowl. Make a well in the center.
In a separate bowl, stir together the cooled butter, milk, eggs, and vanilla.
Add the butter mixture to the well in the flour mixture. Stir just until combined or a few streaks of flour remain.
Gently stir in the blueberries and pineapple. (Save some blueberries to sprinkle on top if you like.)
Divide the dough among the prepared muffin cups, using about 3 tablespoons to fill each cup about 3/4 full. If you reserved and blueberries, scatter them on top of the muffins. Sprinkle the top of each muffin with a pinch or two of sanding sugar if using.
Bake 14 to 18 minutes, or until the edges are browned and a pick inserted into the center comes out clean.
Cool the muffins in the pan on a wire rack for 5-10 minutes before serving.