Preheat the oven to 400 degrees F.
On a sheet pan toss the corn kernels and tomatoes with 1 tablespoon olive oil, 1/2 teaspoon kosher salt and 1/2 teaspoon black pepper. Spread the corn and tomatoes across the pan arranging the tomatoes, so they are cut side up.
Roast the corn and tomatoes for 30-35 minutes until the corn is lightly browned and crisp and the tomatoes are wrinkled but still juicy in the middle.
For the pesto, combine 1 cup roasted corn kernels, 1/3 cup olive oil, 1/2 teaspoon kosher salt, 1/2 teaspoon black pepper, garlic, parmesan and walnuts in a food processor. Puree the ingredients until the pesto is fully combined. (You might see a few corn kernels).
Cook the pasta in salted boiling water until al dente according to package instructions. Drain the pasta in a colander and transfer it to a large bowl.
Stir the pesto into the pasta.
Fold in the remaining roasted corn, tomatoes and scallions.
Divide the pasta into serving dishes and top with additional Parmesan as desired.