Cook the Pasta:
Bring a large pot of salted water to a boil. Add the pasta and cook according to the package directions until al dente (usually 8-10 minutes). Once done, reserve 1/4 cup of pasta cooking water (for the pesto sauce) and drain the rest.

Prepare the Avocado Pesto:
While the pasta is cooking, prepare the avocado pesto sauce. In a food processor or blender, combine the ripe avocado, fresh basil leaves, garlic, pine nuts, parmesan cheese, and lemon juice. Blend until smooth. With the processor running, slowly add olive oil until the pesto reaches your desired creamy consistency. If the sauce is too thick, add some of the reserved pasta water a little at a time to loosen it up.

Combine Pasta and Pesto:
Once the pasta is cooked and drained, return it to the pot or place it in a large mixing bowl. Pour the avocado pesto over the pasta, tossing gently to coat evenly. If necessary, add a little more pasta water to help the pesto coat the pasta.

Season and Adjust:
Taste and adjust the seasoning with salt, pepper, and extra lemon juice if desired. If you like a more intense flavor, you can also add more parmesan or garlic at this point.

Serve:
Plate the avocado pesto pasta in individual bowls. For added flavor and color, you can garnish with cherry tomatoes, roasted vegetables, or a drizzle of olive oil. Serve immediately while warm, or enjoy as a chilled pasta salad for later.