Preheat the oven to 375°F (190°C). Line a muffin tin or use nonstick baking spray. Rinse the raspberries and gently pat them dry. Slice the butter into cubes.
Stir the plant-based milk and apple cider vinegar together to make vegan buttermilk. Let it sit for about 5 minutes to allow time to curdle.
Make the crumble topping by mixing the flour and brown sugar in a bowl. Cut the vegan butter cubes into the mixture with a fork or pastry cutter until it’s crumbly. Cover the bowl and place it in the refrigerator.
Sift the flour into a large mixing bowl and stir in the remaining dry ingredients. Pour the wet ingredients, including the buttermilk, into the mixing bowl.
Combine everything together just until it’s mostly combined. Try not to overmix the batter. Gently fold the raspberries into the batter.
Divide the batter evenly across the muffin liners with a scoop. Each liner will be mostly full. Then top them with crumble.
Bake the muffins on the middle rack for 25 to 30 minutes or until they are a light golden brown. Check that they are done by inserting a toothpick that should come out clean. Let them cool for 10 minutes.