In a small skillet over medium heat toast hazelnuts until skins begin to peel off, about 15 minutes. Remove from heat and cool. Rub off as much skin as possible and chop finely. Transfer to a small bowl.

Bring a large kettle of salted water to a boil and cook pasta according to the package directions, adding the frozen peas when 3-4 minutes of cooking time remain.

While the pasta is boiling, add about a teaspoon of olive oil and stir to coat the nuts, using more oil if needed. Grate in garlic clove using a microplane. Use the microplane to zest the lemon into the mixture. Finally, add parsley and stir until well-combined.

Taste and season with salt and pepper.

Drain pasta and peas, place in a heated bowl, and stir in gremolata to taste.