Preheat oven to 375 degrees Fahrenheit. Grease or line the cups of a 12-cup muffin tin with paper wrappers and set aside.
In a small bowl, combine the granola and milk and let sit for 30 minutes.
In another small bowl, cover the raisins with water and let them soak for 15 minutes. Drain in a mesh sieve or colander and then dry on paper towels.
In a large mixing bowl, whisk together the melted coconut oil, honey, eggs, vanilla extract, and buttermilk.
Add the whole wheat flour, baking powder, baking soda, and sea salt, whisking quickly until well incorporated.
Fold in the granola and raisins.
Using a cookie scoop, portion out the batter into the muffin cups, filling about 3/4 of the way.
Bake for 20 minutes. Allow to sit in the muffin tin for 10 minutes before transferring to a wire rack to cool completely.