Slice tomatoes in half, chunk onion, and dice jalapeño and garlic for tomato sauce. Toss with olive oil and place in a single layer in a large baking dish or sheet tray with sides. Roast until tomatoes are tender and beginning to char, 30-45 minutes. Let cool slightly and place in food processor. Add cilantro and lime juice and run until combined.
Remove husk and silk from corn. Carefully remove corn from cob, using a sharp knife, cutting down the cob. Dice jalapeño into small piece. Heat olive oil in over medium heat in a skillet and add sweet corn and jalapeño. Cook until corn begins to pop, 5-6 minutes. Stir in honey, chili flakes, and lime juice. Continue to cook for 1-2 more minutes. Set aside.
In a sauce pan, toss together cheeses and starch. Turn on heat to low and stir cheese until it starts to melt. Add 1/4 cup of milk and continue to stir until cheese turns into sauce, adding more milk as needed to reach nacho cheese consistency. Add in chili powder, paprika, and garlic powder.
To assemble nachos, place chips in a bowl and pour nachos cheese on top. Sprinkle avocado chunks and black beans, then salsa, and finish with the corn. Sprinkle with a bit of extra cilantro.