Bring a large pot of salted water to a boil over high heat. Once you see a rolling boil, add your 200 g spaghetti and cook for 10 minutes until it's al dente (still has a tiny bit of firmness). Meanwhile, grab a small skillet and heat it over medium-high heat. Don't walk away—you've got about 8 minutes total before you need to drain the pasta.

Toast your 1/4 cup pine nuts in the dry skillet for 2-3 minutes, shaking the pan occasionally so they don't burn. You'll hear them start to crackle when they're ready—that's your signal. Transfer them to a bowl and set aside. I always taste one to make sure it's actually toasted and not just warm.

Add 1 tbsp butter to the same skillet and toss in your 100 g diced chicken breast over medium heat. Sear for 5-6 minutes until the outside gets a little golden and it cooks through—don't mess with it constantly or it won't brown properly. Season with a pinch of salt and pepper while it cooks.

While the chicken's cooking, make your pesto. Add your 2 cups fresh basil leaves, 2 minced garlic cloves, toasted pine nuts, 1/2 cup Parmesan cheese, and 1/2 cup olive oil to a food processor. Pulse until it's mostly smooth with a few small chunks—texture is way more interesting than baby food consistency.

Stir in 1 tbsp lemon juice and 1 tbsp lemon zest to your pesto. Taste it and add 1 tsp salt and 1/4 tsp black pepper, then adjust to what you like. I always add a tiny bit extra salt because Parmesan can sometimes make it taste a little flat.

Drain your pasta when it's done but save about 1/2 cup of that starchy pasta water—trust me on this. The starch helps the pesto coat everything instead of clumping up. Pour the hot pasta into your skillet with the chicken and remove from heat.

Add your pesto to the warm pasta and chicken, then toss everything together using tongs or two forks. Pour in about 1/4 cup of that pasta water and keep tossing—you want it to look creamy and glossy, not dry. If it needs more moisture, add a splash more pasta water. Plate immediately and serve while it's still warm.