Preheat the oven to 425ºF (218ºC). Spray the wells of a 6-count jumbo muffin tin (or line with jumbo liners) generously with non-stick spray. Set aside.
In a medium size bowl, whisk together the flour, baking powder, and salt. Set aside.
2 cups (240g) all-purpose flour, 2 teaspoons baking powder, ½ teaspoon salt
In a large bowl, whisk together the cooled butter, vegetable oil, granulated sugar, and brown sugar until the mixture is smooth. Add the eggs, vanilla, and buttermilk and whisk again until everything is thoroughly combined.
¼ cup (57g) unsalted butter, ¼ cup (56mL) vegetable oil1, ½ cup (100g) granulated sugar, ½ cup (100g) firmly packed light brown sugar, 2 large eggs, 2 teaspoons vanilla extract, ½ cup (120mL) buttermilk2
Gently fold the dry ingredients into the wet ingredients. When the batter is mostly combined, add the chocolate chips and continue stirring gently until everything is incorporated, being careful not to overmix. Allow the muffin batter to rest for 15-20 minutes (you do not need to cover it).
1 cup (170g) semi-sweet chocolate chips3
After the batter has rested, spoon the batter evenly into the 6 wells. Two ice cream scoops full works best, totaling about ½ cup of batter in each well. Sprinkle with additional chocolate chips and sanding sugar.
coarse sanding sugar
Bake the muffins for 7 minutes, then reduce the oven temperature to 350ºF (177ºC) without opening the door, and bake for another 20-22 minutes. Muffins are done when a toothpick inserted into the center comes out mostly clean and the tops are golden brown. Remove from the oven and allow them to cool in the pan for no more than 10 minutes before removing from the pan to cool completely on a wire rack. Muffins stay fresh covered at room temperature up to 5 days or in the refrigerator up to 1 week. Muffins freeze well, up to 2 months. Thaw in the refrigerator or heat in the microwave about 15 seconds before serving.
Notes
Oil: you can use vegetable oil, canola oil, or melted coconut oil in this recipe.
Buttermilk: if you don't have buttermilk on hand, you can make your own: see my post about homemade buttermilk.
Semi-sweet chocolate chips:I like a mix of standard and mini size, about ¾ cup standard and ¼ cup mini measured into the same measuring cup.
Amp up the flavor: if you're looking for some real pizzaz in your muffins, consider adding ground cinnamon and/or ground nutmeg. Just ½ to 1 teaspoon of cinnamon and/or ⅛ teaspoon of ground nutmeg will bring even more authentic "bakery style" flavor to these muffins.
Standard size muffins: for standard size muffins, bake in a 12-count muffin pan and reduce total baking time to 20 minutes (initial bake time is still 7 minutes). This recipe will make about 14 standard size muffins.
Mini-muffins: use only mini-chocolate chips and bake for 12-13 minutes at 350°F (177ºC) for the entire time. Recipe yields about 40 mini muffins.
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.