Preheat oven to 325 degrees F. Line a baking sheet with parchment paper or a silicone baking mat.Sprinkle shredded cheeses evenly over the entire sheet pan. Top with seeds, distributing them evenly over the entire pan. Sprinkle with sea salt.Bake for 35 to 40 minutes, rotating the pan once part way through. The cheese will have melted and darkened to a light golden brown, the color of butterscotch candy. Take care not to let it bake too long or the cheese may taste burnt.Remove from oven and let cool completely before breaking up into bite-size pieces.Store crackers in an airtight container at room temperature or in the refrigerator for up to 7 days.