Place corn under broiler and rotate ever 30 seconds or until each side begins to blister and char.
Slice kernels off of cobs and place into a mixing bowl, discarding cobs.
Add to the mixing bowl with the corn, the cotija, Parmesan, cilantro, lime zest and juice, and ¼ cup mayonnaise and stir together. Season with salt and pepper.
Place all spices for spice blend into a small mixing bowl and whisk together.
To assemble: Spread a small amount of mayonnaise onto each crostini and sprinkle with the spice blend.
Top each prepared crostini with a spoonful of the corn mixture and serve immediately.