Preheat oven to 375 degrees F. Line muffin tin with liners.
Combine dry ingredients in a large bowl including whole wheat flour, sugar, cinnamon, baking powder, baking soda, and salt.
In a separate bowl, whisk together buttermilk, vegetable oil, egg, and vanilla. Add wet ingredients to dry ingredients, stirring just until combined. Gently fold in chopped strawberries and dark chocolate chunks.
Fill the muffin pan with batter. Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Remove from the oven and cool the muffins completely on a wire rack.