Gather the ingredients. In a large pot filled with water cook pasta according to the package's directions. Cover the pot with a lid to bring water to boil faster. While pasta is cooking, wash and rinse the beet greens. Remove the large stems.
In a food processor, place beet greens and pecans. Pulse several times till crushed, open, scrape the sides. Add olive oil and salt, pulse a couple of times.
Shred the cheese. Drain tuna, using fork mush into smaller pieces while still in the can—Preheat the oven to 375F degrees.
Once pasta is cooked, drain and place in the oven-safe baking dish. Add pesto, one cup of shredded cheese, drained tuna. Mix well to combine. Add one more cup of cheese as the top layer, spread evenly.
Bake for 10 minutes on the second to the top shelf, so the cheese melts. Serve warm.