1 cup semisweet chocolate chips
1/4 cup butter
2 1/2 cups graham cracker crumbs
2 cups miniature marshmallows
1 can sweetened condensed milk
1 teaspoon vanilla extract
1 cup milk chocolate chips

Lightly butter a 9 x 13-inch pan.

In small saucepan, over very low heat, melt together butter and chocolate chips, stirring often.

In large bowl, combine graham cracker crumbs with marshmallows; stir in sweetened condensed milk and vanilla extract until crumbs are all moistened. Stir in melted chocolate until well combined. Fold in milk chocolate chips. Pat all into pan. Let stand at room temperature about 2 hours before cutting. Chill if a firmer brownie is desired.