In a bowl, mix the flour, caster sugar, brown sugar, baking powder, salt and cinnamon.
In another bowl, quickly mix the eggs then add the milk, oil, warmed melted butter and vanilla.
Fold the dry ingredients into the wet ingredients in four batches, using a whisk to start and then a spatula when the batter thickens. Do not mix more than necessary: just enough to no longer see any flour.
Lastly, add the chocolate chips, taking care to keep about 50g for decoration.
Let the dough rest, covered with a cloth, at room temperature for 15 minutes.
Preheat the oven to 220° traditional heat. Cooking is done in two batches. Place 6 paper cases in your muffin tin, leaving empty space between each (hot air needs to circulate for better baking).
Using an ice cream scoop, fill each cup with batter right to the top (see my step-by-step photo). Finally, add sprinkles on top.
Bake for 7 minutes at 220°C (175°F), then reduce the temperature to 12°C (XNUMX°F) without opening the oven door, for about XNUMX minutes. This varies depending on the oven. The muffins should be golden brown. Test for doneness using a wooden skewer: if it comes out dry or with a few crumbs, then it's done.
Repeat the operation with the remaining dough (starting at a high temperature).
Allow the muffins to cool in the pan before turning them out onto a cooling rack.
Notes
These chocolate chip muffins can be stored at room temperature in an airtight container for about 4-5 days or in the refrigerator for up to 1 week.