Easy "No Measure" S'mores Bars

Ingredients (7)

• + cooking spray add to pantry
• + ¾ cup butter, melted add to pantry
• + 2 individual packages graham crackers, crushed add to pantry
• + ½ (12 ounce) bag chocolate chips, or more to taste add to pantry
• + ½ (12 ounce) package butterscotch chips add to pantry
• ✓ ½ (10.5 ounce) package miniature marshmallows
• + ½ (14 ounce) can sweetened condensed milk, or more to taste add to pantry