Preheat oven to 425˚F. Lightly grease a muffin pan or line with cupcake liners.
Place the peaches in a large bowl. Sprinkle with cinnamon and ¼ cup of the brown sugar and stir to combine. Set aside.
Prepare the crumble topping by whisking together ½ cup of the flour, remaining ¼ cup of brown sugar, and ¼ cup of the granulated sugar. Use a fork to incorporate 4 tablespoons of the butter until there are no large chunks of butter. Set aside.
Melt the remaining 4 tablespoons of butter, and set aside to cool. In a large bowl, whisk together the almond milk, eggs, vanilla, and cooled melted butter. In a medium bowl, whisk together the last 2 cups flour, baking powder, salt, and last ½ cup of granulated sugar. Fold in the peaches and all the juices.
Spoon the batter into the muffin tin, then top each with the crumble mixture.
Bake for 6 minutes, then reduce heat to 350˚F. Bake for 12 more minutes, until golden brown and a toothpick comes out clean.
Allow to cool for 5 minutes, then transfer to a wire rack. Serve warm or at room temperature.