Preheat the oven to 300 degrees F. Coat a parchment-lined baking sheet with 1/4 cup of the olive oil.
Cut a 10-inch circle in the top of the pumpkin and remove the top. Scrape out the pulp and seeds with a large spoon and remove to a bowl. Separate the seeds from the stringy pulp, then rinse the seeds in a colander under cold water. Shake the seeds dry; don't blot them with paper towels--they will stick.
Spread the seeds in a single layer on the prepared baking sheet and bake until beginning to dry out, about 30 minutes.
Meanwhile, whisk together the tomato paste, oregano, granulated garlic, red pepper flakes, remaining 1/4 cup olive oil and some salt and pepper in a medium bowl. Add the baked pumpkin seeds and toss until evenly coated. Spread the seeds back on the original baking sheet and continue to bake until the seeds are golden brown, another 20 minutes.
Sprinkle the seeds with the Parmesan and continue to bake until the cheese starts to turn a light golden brown, about 5 minutes more. Cool before serving.
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