Preheat your oven to 375°F.

Line a standard 12-cup muffin tin with grease-proof muffin liners, spray the liners with cooking oil spray, and set the tin aside.

In a 4 cup measuring cup or other medium-size bowl with pour spouts, whisk together the milk, butter, eggs, granulated sugar, and brown sugar. Set the mixture aside.

In a large mixing bowl, place the flour blend, xanthan gum, baking powder, and salt, and whisk to combine.

Create a well in the center of the dry ingredients and pour in the wet ingredients. Mix until just combined. The batter will be thick but not stiff.

Add the chopped strawberries and fold them gently into the batter, trying not to squish the berries.

Fill the prepared wells of the muffin tin completely full with batter. You should have 12 muffins.

With wet fingers or a wet spoon, smooth any really uneven bits of batter in the middle wells to distribute the batter more or less evenly.

Chop 2 optional extra strawberries and distribute evenly on top of batter in each well. Press down gently to help them adhere.

Sprinkle the optional coarse sugar lightly on top of the batter in each well.

Place the muffin tin in the center of the preheated oven.

Bake until the tops are lightly golden brown and a tester comes out clean when inserted into the center of the middle muffin (about 25 minutes).

Remove the muffin tin from the oven and allow the muffins to cool in the tin for 5 minutes.

Gently lift each muffin out of the tin, and transfer it to a wire rack to allow it to cool completely.