Prep your pan. Heat the oven to 350°F (175°C). Grease each mini loaf cavity well, then line with a parchment strip for easy lifting.
This helps prevent sticking and keeps edges neat.
Combine dry ingredients. In a large bowl, whisk flour, granulated sugar, brown sugar, baking powder, baking soda, and salt until there are no sugar clumps.
Mix the wet ingredients. In a separate bowl, whisk melted butter, oil, eggs, buttermilk, and vanilla until smooth. The mix should look creamy and uniform.
Bring it together. Pour the wet mixture into the dry ingredients. Stir with a spatula until just combined. Do not overmix—a few small lumps are fine and keep the crumb tender.
Fold in add-ins (if using). Gently stir in chocolate chips, berries, nuts, or dried fruit.
Aim for even distribution without stirring too much.
Fill the pan. Divide the batter evenly among the cavities, filling each about 2/3 to 3/4 full. This gives them room to rise without overflowing.
Bake. Place the pan on the center rack and bake for 18–24 minutes, depending on your oven and pan size. The loaves are done when a toothpick comes out with a few moist crumbs, not wet batter.
Cool. Let the mini loaves rest in the pan for 8–10 minutes, then lift out using the parchment strips and transfer to a wire rack to cool completely.
Glaze or finish. Whisk powdered sugar with milk or lemon juice until pourable.
Drizzle over cooled loaves. For extra flair, add lemon zest, chopped nuts, or a few chocolate shavings on top.