Heat grill to high
Combine the asparagus
, basil, garlic and pine nuts in a food processor
a few times to coarsely chop
. With the motor running, slowly add the oil and process until emulsified. Season with salt and pepper and transfer the pesto to a bowl. Stir in the Pecorino Romano.
shell on the grill. Grill
until slightly crisp
, about 1 minute. Remove the shells and spread each with the pesto
. Top with the fontina, return to the grill, close the cover and continue cooking until the cheese has melted, 2 to 3 minutes. Remove from the grill and sprinkle with the remaining Romano cheese
and chopped fresh basil
. Slice each flatbread
into bite-sized pieces.