Preheat the oven to 400° and line a muffin tin with 4 paper liners.

In a small bowl, whisk together the flour, baking powder, cinnamon and salt.

In a medium bowl, beat together with an electric mixer the butter and sugar until fluffy and well-blended, about 3-4 minutes.

Add the egg white and beat to combine.

Add half of the flour mixture to the butter mixture. Mix until blended, and then add the buttermilk, and beat until combined. Add the remaining flour and beat until just combined—do not over mix.

With a spatula, fold in the diced strawberries.

Divide the batter between the 4 muffin cups and sprinkle turbinado sugar evenly over each muffin before placing in the oven. Bake 18-20 minutes, or until a toothpick inserted comes out clean.