Beet Pesto Pasta

INGREDIENTS

• 3 large purple beets, tops trimmed
• 3 cloves garlic
• 1⁄2 cup whole raw pistachio nuts, plus 2 tablespoons chopped, for garnish (or you can use peeled almonds)
• 1⁄4 cup lemon juice
• 1⁄4 cup olive oil
• 1 cup finely grated Parmesan
• kosher salt
• 1 pound spaghetti