Preheat the oven to 350 degrees Fahrenheit. Line a 12 cavity muffin tin with liners and set aside.

In a small dish, mix together the brown sugar and cinnamon for the filling and set aside.

In a second dish, mix together all ingredients for the streusel until crumbly and well combined. Set aside.

In a mixing bowl, whisk together the melted butter and sugar. Add in the eggs, greek yogurt, milk and vanilla. Whisk until smooth.

Whisk in the flour, baking powder, baking soda, salt and cinnamon until smooth.

Scoop about 1 ½ tablespoons of batter into each muffin tin. Sprinkle each with the cinnamon sugar filling. Top with the remaining muffin batter. Use the back of the spoon to spread smooth- it helps to grease the spoon a bit.

Top each muffin with the streusel, about 1 ½- 2 tablespoons on each.

Bake on the middle rack for 22-25 minutes or until a toothpick comes out clean. let cool in the muffin tin for about 15 minutes, then transfer to a wire rack until fully cooled.

Whisk together the ingredients for the glaze, adding more milk as needed to thin. Once the muffins have cooled, drizzle on top. Enjoy!