2 teaspoons fennel seeds
1/2 pound ground pork
3 tablespoons plus 1 teaspoon olive oil, divided
1 1/2 teaspoons kosher salt, divided, plus more
3/4 teaspoon freshly ground black pepper, divided, plus more
1/2 medium onion, thinly sliced
2 garlic cloves, finely chopped
4 ounces asparagus (about 4 medium spears), trimmed and cut diagonally into 1-inch pieces
8 large eggs
1/4 cup grated Parmesan
3 tablespoons heavy cream
1/4 cup beet green pesto (see headnote) or 1 tablespoon finely chopped herbs plus 2 tablespoons olive oil
Preheat oven to 350°F. Heat a 10" ovenproof skillet over medium-high. Add fennel seeds and toast, stirring constantly, until fragrant, 1 minute. Add pork, 1 tsp. oil, 1/2 tsp. salt, and 1/4 tsp. pepper and cook, breaking up pieces with a wooden spoon or spatula, until browned and cooked through, about 5 minutes more. Scrape pork mixture into a medium bowl.
Heat 1 Tbsp. oil in same skillet over medium. Add onion, 1/4 tsp. salt, and 1/4 tsp. pepper and cook, stirring occasionally, until softened and translucent, about 5 minutes. Add garlic and cook, stirring constantly, until fragrant, 1 minute. Add asparagus and cook, stirring occasionally, until crisp-tender and bright green, 3–5 minutes more. Add vegetable mixture to pork mixture, stir to combine, and let cool slightly. Wipe out skillet and reserve.
Meanwhile, whisk eggs, Parmesan, cream, 3/4 tsp. salt, and 1/4 tsp. pepper in a large bowl. Add pork and vegetable mixture and stir until well combined.
Heat 2 Tbsp. oil in reserved skillet over medium. Add egg mixture and cook, without stirring, until edges have started to set and pull away from pan, about 7 minutes. Transfer frittata to oven and bake until set, 10–12 minutes.
Season with salt and pepper, cut into wedges, and drizzle with leftover beet green pesto, if using, or herbed oil. Serve warm or at room temperature.