Preheat oven to 325°. Fill a large pot of with about 1-inch of salted water and bring to a boil over high heat.
While waiting for water to boil, remove stems from kale and roughly chop. Place on a sheet pan and toss with olive oil and a pinch of salt and pepper. Bake for 15-20 minutes until browned and crisp.
When water boils, cook pasta per package directions for al dente. Drain and return pasta to pot.
While pasta is cooking, melt butter in a medium saucepan over medium heat. Add garlic and cook briefly until fragrant.
Add flour and cook for 1 minute while stirring. Gradually pour in milk while stirring. Reduce heat as needed and simmer, stirring occasionally, until slightly thickened, about 4-5 minutes. Add parmesan and ¼ tsp pepper to the saucepan, and cook until cheese is incorporated into sauce. Remove from heat.
Add sauce to the pasta and mix together. Add salmon and zest from half the lemon. Juice lemon and add 1 tbsp lemon juice. Toss to combine. Adjust seasoning as needed with salt, pepper, and lemon juice. Divide pasta amongst serving bowls and top with crispy kale.