Preheat oven to 350 degrees. Lightly grease muffin tins. Melt the butter in a saucepan over low heat and set aside to cool. In a medium-sized bowl, mix the flour, baking powder and salt. Set aside. In another medium-sized bowl, whisk the egg. Add the sugar and the vanilla and continue to whisk until thick and creamy. Add the almond milk, butter and yogurt and stir to combine. Combine the egg mixture and the flour mixture until fully incorporated. Fold in the fruit and set aside. To make the crumble, add all ingredients to a small bowl and mix by hand until a crumble begins to form.
Pour the batter into the muffin tins until they are about 3/4 full. Top each muffin with a generous amount of the crumble. Bake the muffins for 35-40 minutes, or until the muffin and the crumble are golden brown and a toothpick inserted into the center of each muffin comes out clean.