Make the streusel topping by combining the dry ingredients in a small mixing bowl. Slowly add the melted butter, stirring with a fork until mixture is combined and reaches a crumbly consistency.

Preheat your oven to 425 degrees F.

Make the filling for your muffins by placing 1 c sliced strawberries and 1 tsp sugar in a small saucepan over medium heat. Cook for about 5 minutes, stirring frequently, until mixture is thickened and the strawberries begin to break down. Set aside and let cool to room temperature. (Place in the fridge for a few minutes to hurry the process along if need be.)

In a large mixing bowl stir together the flour, baking powder, and salt.

In a separate bowl whisk the eggs and remaining sugar until thickened. Slowly add the butter and oil to the egg mixture, whisking as you go. Whisk in the Greek yogurt, milk, and vanilla.

Fold this egg mixture into your flour mixture. Fold in the remaining c of strawberries, being careful not to over-mix your batter. It's okay for it to be a little lumpy.

Prepare your muffin pan, either by greasing the pan or using paper muffin cups.

Use a spoon to divide the batter between muffin cups. The batter should completely fill the cups.

Evenly divide the cooled strawberry filling mixture between the muffins, using a chopstick or skewer (or your finger) to poke the filling down into the strawberries. This part doesn't have to be perfect - any berries left showing through will make the muffins look pretty!

Sprinkle the streusel topping over the top of your strawberry-filled muffin cups.

Bake in your preheated oven for about 17 minutes, until a toothpick inserted in the center comes out with just a few crumbs on it.

Remove from the oven and let cool in the muffin pan for 5 minutes before removing to a cooling rack.