Preheat your oven to 350°F (180°C) or 160°C fan. Line a 12-hole muffin pan with paper liners.
Mix the dry ingredients: In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and broken-up trail mix.
Mix the wet ingredients: In another bowl, whisk together the yogurt, milk, oil, and vanilla.
Combine: Pour the wet mixture into the dry ingredients. Stir gently with a spoon or spatula until just combined. Don’t overmix.
Scoop and bake: Divide the batter between the muffin cups (about ¾ full). Add a little extra trail mix on top if you like.
Bake for 20 to 22 minutes, or until a toothpick comes out clean.
Cool in the pan for 5 minutes, then move the muffins to a wire rack to cool completely.