Generously season the chicken with salt and pepper. Heat a skillet over medium-high heat, and add 1 tablespoon of butter. Once the butter is hot and bubbly, add half of the chicken. Brown both sides of the chicken, this will take about 2 minutes per side. Remove the browned chicken from the skillet, melt the remaining butter, and brown the remaining chicken. Remove the second batch of chicken from the skillet, and set aside.

Pour the lemon juice, broth, and wine into the skillet. Bring to a simmer, and add all of the chicken. Cover, reduce the heat to low, and let cook for 10 minutes.

Meanwhile, bring a pot of salted water to a boil so that you can cook the pasta. Fresh tagliatelle will cook in just about 2 minutes. One minute before you pour the pasta into the water, add the asparagus to the pot with the chicken, and put the lid back on the skillet. Then pour the pasta into the water, and let it cook for 1 minute. You want to slightly undercook the pasta because you will simmer it in the sauce. Drain the pasta.

Pour the pasta, creme fraiche, and parsley into the skillet (if you don't have room in the skillet, pour everything into the pot you used to boil the pasta). Stir, and let simmer for 1 minute. Serve immediately.