1. Preheat an oven to 350 degrees F (175 degrees C). Line a 13x9-inch pan with lightly-greased parchment paper; an inch or so of parchment paper should stick up on 2 sides to form lifting handles.
2. Mix the quick-cooking oats, old-fashioned oats, pumpkin seeds, almonds, mixed nuts, cranberries, and sweetened condensed milk together in a bowl; spread into the prepared pan, evenly pressing into the corners and out to the sides.
3. Bake in the preheated oven until the edges are golden brown, 20-25 minutes, using slightly less time for chewier bars and slightly more time for crunchier bars.
4. Allow the the bars cool for 5 minutes in the pan before using the parchment paper to lift them from the pan. Use a sharp knife to cut into bars. Let the bars cool completely and store in an airtight container.