Preheat your oven to 350F/175C. Line a muffin/cupcake pan with muffin liners (or grease it with butter and flour or baking spray).
Melt the butter and set aside. Don’t let it cool enough to solidify, but do let it cool somewhat before using.
Using a large fine mesh sieve, sift then whisk together the flour, cocoa powder, baking powder, and salt. You can also add a dash of cinnamon if you’d like. Set aside.
In a medium to large mixing bowl, whisk the Greek yogurt, vanilla, eggs, and oil until well blended. Slowly pour in the butter while whisking quickly.
Add the sugar and brown sugar to the wet ingredients and whisk for about 1 minute. You can whisk it by hand or, if using a stand or hand mixer, mix on medium.
Fold in the flour mixture gently until mostly combined, with some visibly dry flour in spots. Fold in the chocolate chips until well-distributed. This step will cause the rest of the flour to mix in, but it should still have some lumps in it.
Divide between your prepared muffin liners/pan. Top with some more chocolate chips.
Bake for 18-23 minutes, until matte on top and a toothpick inserted in a middle muffin comes out with some moist crumbs. Check early so it doesn’t over bake. Let muffins cool in pan 5-10 minutes. Remove and let either serve immediately or let cool completely before storing in an airtight container.
