Preheat your oven to 350°F (176°C). Line a muffin tin with muffin liners or grease the cups and set aside.

In a medium-sized bowl, combine the all-purpose flour, cocoa powder (sifted to avoid lumps), baking soda, baking powder, and salt. Set these dry ingredients aside.

In a microwave-safe bowl or using a double boiler, melt the butter until just melted. Stir in 1 1/4 cups semi-sweet chocolate chips until you have a smooth, glossy chocolate mixture.

In a large mixing bowl, combine the warm (not hot) melted chocolate mixture with the white sugar and dark brown sugar. Stir continuously for about 1–2 minutes until the sugars dissolve slightly.

Add in the oil and whisk until well incorporated.

Allow the mixture to cool for about 5 minutes if it’s still warm, then whisk in the eggs one at a time, followed by the vanilla extract. Mix until smooth and glossy.

Gently add the dry ingredients to the wet mixture. Using a spatula, fold until just combined, being careful not to over-mix to keep your muffins tender.

Fold in the additional 3/4 cup chocolate chips if using for extra chocolatey bites.

Fill each muffin liner about 3/4 full with batter. Add a few more chocolate chips on top if desired for a bakery-style finish.

Bake in the preheated oven for 25–35 minutes. For fudgy muffins, bake on the lower end; for more cake-like, go longer. Insert a toothpick into the center—moist crumbs are perfect!

Remove from oven and cool in the tin for 10 minutes before transferring muffins to a wire rack. Let cool completely before serving for best texture.