I recommend letting the chicken sit out until it is ready to cook. Letting it come slightly to room temp will shorten the cooking time, provide an even cook, and thus maintain moisture, providing a juicy, perfectly cooked chicken breast. In a large saucepan or Dutch oven, bring water and salt to a boil. Cut a 2” piece of jalapeño pepper and finely mince it to make about 1 tablespoon of minced jalapeño.
Prepare the cream sauce by adding garlic cloves, minced jalapeños, peppercorns, and sea salt to a mortar and crush into a paste with a pestle. Add olive oil once the peppercorns are mostly broken down, and continue to crush until the peppercorns and salt are pulverized. Set aside. Grate the Asiago cheese into a bowl and set both aside. Add the pasta to the water and boil Al dente according to the package instructions.
Use this time to shred the cheddar cheese and jalapeño slices that will be added as a finishing touch. When the pasta is done, pour into a colander and place under running cold water. Return the pan to the stovetop over high heat. Add the butter to the pan with ½ of the Italian seasoning and the minced garlic.
Add the chicken to the pan and sprinkle the remaining Italian seasoning over the top. Cover and cook for 3 minutes. Turn the chicken over and cook for an additional 3 minutes. Remove the chicken from the pan and place onto a wooden cutting board. Use an upside down mixing bowl to create a dome over the chicken to trap the heat. Next, prepare the sauce by adding the garlic jalapeno paste to the pan and sauté for 2 minutes. Sprinkle the flour over the pan and stir until combined. Cook for about one minute or until the flour starts to bubble
Slowly incorporate the heavy cream and milk into the sauce. Whisking constantly to prevent lumps. Once the milk and cream are fully incorporated, reduce the heat to low and stir in the shredded asiago cheese and cayenne pepper. Stir until melted, about 1 minute. Add the pasta to the cheese sauce and toss to coat. Turn off the heat and cover. Thinly slice the chicken breast. Add the chicken, shredded cheddar cheese, and jalapeño slices to the pasta.
Transfer any leftovers into an airtight container once the rattlesnake pasta has completely cooled. Then store it in the fridge to enjoy for up to 3 to 4 days.