Grease a 9 x 13 pan

Place Rice Krispies, quick oats, chocolate chips, 1/2 the M&M's, and salt in a bowl and toss.

In a large saucepan, melt butter, peanut butter, and marshmallows until the marshmallows are completely melted.

Pour melted butter/marshmallow mixture over the cereal mixture and toss until the cereal and oats are evenly coated. Add additional M&M's and other add-ins, like dried fruit or raisins if desired

Using a greased spatula, press everything into the 13X9 pan. Let the cereal treats sit for at least 30 minutes before cutting them into squares.