Rigatoni with Brussel Sprouts and Leek

Original recipe here:  https://www.bonappetit.com/recipe/rigatoni-with-brussels-sprouts-parmesan-lemon-and-leek

I'd give this 3/5.  I'm looking for something more flavorful.  Though I definitely made some mistakes, I'm not sure doing it right would have saved the recipe for me.

I didn't have a lemon (so no lemon zest).  I also added 1 chicken thigh (about 1/3 lb) cut into small cubes.

I more or less followed the recipe.  I quartered the brussel sprouts instead of halving them.  True medium rather than medium high on my stove would have been better.

I added the chicken cubes mid-way through the browning of the garlic & chopped leek.  My garlic never did brown.  I also added maybe 1 C wine and reduced.

Would have liked a little kick; maybe some red pepper flakes.  Lemon would have gone well.