Preheat oven to 375F degrees & line 2 muffin pans with cupcake liners; 6 per tin and spreading them out across the tins. This will help your muffins rise nicely.

Make your crumble; In a medium bowl, whisk together flour, sugar, cinnamon and nutmeg. Pour in melted butter and mix with a spoon until a crumbly mixture forms. Set aside.

Make your muffins; In a large bowl, whisk together flour, sugars, baking soda, baking powder, salt and cinnamon until combined. Make a well in the center of the dry ingredients and set aside.

In a medium bowl, whisk together Greek yogurt, eggs, vanilla and lemon zest until combined. Pour in melted butter and whisk until smooth. Pour wet ingredients into the well of the dry ingredients. Use a spatula to gently fold the wet ingredients into the dry until just starting to come together. Add in blackberries and fold them in until everything is just combined. It is okay if there are still a few streaks of flour.

Tip: be careful not to overmix your muffin batter, as this can result in tough muffins.

Scoop muffin batter into prepared cupcake liners, filling just below the top. Sprinkle the tops of each muffin with a generous amount of prepared crumble to cover the batter.

Place both racks in the oven to bake for 16-20 minutes or until the muffins are golden brown and the tops spring back to the touch.

Remove from oven and allow to cool for a few minutes.

Meanwhile, whisk together all of the ingredients for your glaze until smooth. Drizzle the glaze over the tops of the muffins, and let it set for another few minutes before serving.

Enjoy!