Preheat oven to 350 degrees and line a muffin tin with paper wrappers.

Stir together your flour, sugar, baking powder, baking soda, and salt.

In a separate bowl, stir together melted butter, sour cream, vanilla, and the egg. This will be a thick mixture, so keep stirring until mixed well.

Slowly add wet ingredients into the dry ingredients. Stir together until well incorporated. This will be a very thick batter.

Fold in the strawberries.

Evenly split batter between the 12 muffin wells.

To make the streusel, mix together the oats, brown sugar,melted butter and pinch of cinnamon.

Spoon 1 tsp. of mixture over each muffin well. Mix together the remaining cinnamon and sugar and sprinkle over each muffin.

Bake for 25 minutes or until golden brown and a toothpick inserted comes out clean.

Let cool for five minutes and then remove from tins. Let cool completely before eating so that the strawberries firm back up.

(Note: Due to the topping, these muffins may sink a little on the top and will not be a perfectly domed muffin.)