Preheat your oven to 375°F (190°C). Prepare your muffin tin by lining it with paper liners or greasing each cup.

Dice the fresh strawberries into small pieces and pat them dry.

Melt the butter in a microwave-safe bowl and allow it to cool slightly.

Sift together the muffin mix, baking powder, salt, and sugar in a separate bowl.

Whisk together the eggs, milk, vanilla extract, and melted butter in another bowl.

Gently combine the wet mixture with the dry ingredients using a spatula.

Fold the diced strawberries into the muffin batter.

Spoon the muffin batter into the prepared muffin tin. Fill each cup about ¾ full and sprinkle coarse sugar on top if using.

Bake for 20-25 minutes until golden brown. Test for doneness with a toothpick.

Let muffins cool in the pan for 5 minutes, then transfer to wire racks to cool completely.