Snack Mix Squares

2 1/2 cups halved pretzel sticks
2 cups Corn Chex®
1 1/2 cups M&M's®
1/2 cup butter or margarine
1/3 cup creamy peanut butter
5 cups miniature marshmallows

In a large bowl, combine pretzels, cereal and M&M's®. In a large saucepan over low heat, melt butter and peanut butter. Add marshmallows; cook and stir until marshmallows are melted and mixture is smooth. Pour over pretzel mixture; stir to coat. Press into a greased 13 x 9-inch baking pan. Cool until firm; cut into squares.