Melt butter and baking sqaures in a microwave safe bowl. In the mixing bowl, cream melted butter and chocolate mixture. Add in sugar and vanilla and beat until fluffy, about 2-3 minutes. Add in eggs, beating one at a time. Add flour and stir just until combined. Fold in chocolate chips. Fold in marshmallows.
Pour into greased 9 x 13 baking dish (I used a 10 x 10 square cake pan). Bake for 35-45 minutes, or until just barely done.
Course: Dessert
Cuisine: American
Did you make this recipe?
Be sure to follow @howsweeteats on instagram and tag #howsweeteats. You can also post a photo of your recipe to our facebook page. I appreciate you so much!