Preheat oven to 350 degrees F (177 degrees C).
Combine all the ingredients for the crumble topping in a food processor. Pulse until they become a crumbly texture (2-3 minutes). Set aside.
Combine melted butter, coconut milk, sugar, light brown sugar, vanilla extract, salt, eggs, lemon juice, and lemon zest in a large bowl. Whisk until well incorporated.
Add the baking powder and sweet rice flour. Fold the dry ingredients into the wet ingredients.
Lastly, gently fold the blueberries into the batter.
Grease a muffin pan with oil or butter. Scoop batter into the muffin pan. Divide the crumble evenly among the muffins. Smack the muffin pan on the counter 1-2 times to get rid of excess air bubbles.
Bake for 40-45 minutes until the edges start to brown.
Cool for 10 minutes before serving.