In a medium saucepan, heat 1 tablespoon oil over medium heat. Add leek and cook, stirring occasionally until soft but not browned, about 5 minutes. Add stock, cream, vodka, and a pinch of salt. Increase heat to medium-high, bring to a boil and cook, stirring occasionally until reduced to 1 1/2 cups, about 30 to 40 minutes. Remove sauce from heat and stir in lemon zest, dill, chives and red pepper flakes. Set aside

Meanwhile bring a large pot of salted water to a boil. Cook pasta according to package instructions. When cooked al dente, drain and return to pot. Stir in 1/2 cup cream sauce and cover to keep warm.

Heat remaining 1 tablespoon oil in a frying pan over med-hi heat. Add shrimp and cook until pink and opaque. about 1 to 2 minutes. Add peas and saute another 30 seconds. Add shrimp and peas to pasta. Add remaining sauce and toss to coat. Season to taste with salt and pepper. Divide among serving plates. Serve immediately with freshly grated parmesan cheese, if desired.