12 oz. penne pasta
8 oz. green beans, trimmed and halved
4 slices bacon
1 lb. boneless, skinless chicken breasts, cut into 1/2-inch chunks
2 tbsp. fresh lemon juice
1 large egg yolk
2 tbsp. half-and-half
5 oz. baby spinach
1 oz. Parmesan, grated (about 1/2 cup)
2 scallions, thinly sliced
Cook pasta per package directions, adding green beans to the pot during the last minute. Reserve 1/2 cup cooking water; drain, then return pasta and green beans to the pot.
Meanwhile, in a large skillet on medium, cook bacon until crisp, 3 to 4 minutes per side. Transfer to a paper towel-lined plate and break into pieces when cool. Discard all but 1 Tbsp bacon drippings and return pan to medium.
Cook chicken until golden brown and cooked through, tossing once, 6 to 8 minutes; remove from heat and toss with lemon juice. In a small bowl, whisk egg yolk and half-and-half. Toss egg mixture with pasta and green beans, then fold in chicken, spinach, Parmesan, and 1/4 cup pasta water, tossing to coat and adding more pasta water if needed. Fold in scallions and top with bacon.