Preheat the oven (or even your grill!) to 400 degrees F. Line a baking sheet with parchment paper.
Spread the tortilla chips out on the baking sheet, in as much of a single layer that you can.
In a large bowl, toss the crab with the old bay, half of the green onion and the juice of 1 lime. Spread the crab mixture out over the tortilla chips.
Top the crab with the cheddar and fontina cheese.
In a large bowl, combine the remaining green onions, remaining lime juice and the tomatoes, jalapenos, shallots, radish and cilantro. Add a big pinch of salt and pepper. Stir. Add more lime if needed.
Place the sheet pan in the oven and bake for 8 to 10 minutes, until the cheese is melted and all the chips are warm.
Remove the pan and top with the salsa. Serve immediately!