• First things first, fill a large pot with generously salted water and bring it to a rolling boil. Add your pound of penne and cook according to the package directions, until it's just al dente (meaning it still has a slight bite). Right before you drain it, use a mug to reserve about one cup of that starchy pasta water. That stuff is liquid gold and perfect for thinning out a sauce later if needed.

Build the Signature Asiago Cream Sauce

• While the pasta cooks, place your large skillet or Dutch oven over medium heat. Add the olive oil and butter. Once the butter is melted and sizzling, add the minced shallot and cook for about 2 minutes, stirring frequently, until it softens and turns translucent. Now, add the minced garlic and cook for just another 30 seconds until that nutty, irresistible aroma hits your nose. Don't let the garlic brown or it will turn bitter.
• Tumble all the spices directly into the pan—the salt, chili powder, paprika, sugar, and cayenne. Stir constantly for about 45 seconds. This quick toasting step is a game-changer; it wakes up the spices and creates a hugely fragrant, smoky base layer of flavor that makes the whole dish pop.
• Now sprinkle the flour over the aromatics and spices. Immediately begin whisking it into the butter and oil. Keep whisking for about 60-90 seconds. You’re cooking out the raw flour taste and creating a paste—this is your roux! It should look a little something like thick, wet sand and smell toasty and nutty. This little step is our guarantee of a thick, stable sauce.
• Okay, time to turn that paste into liquid velvet. While whisking continuously, pour ¼ cup of the chicken stock into the pan. The mixture will instantly seize up and thicken—this is exactly what you want! Now, slowly begin pouring in the remaining ½ cup of stock, whisking constantly to eliminate any lumps. Once it’s smooth, gradually whisk in the heavy cream and milk.
• Bring the sauce to a gentle simmer (you'll see those lazy bubbles appear). Let it bubble gently for 3-4 minutes, stirring often, to allow the roux to thicken it to a beautiful consistency. It should be thick enough to coat the back of a spoon. Now for the most important part: turn the heat down to the absolute lowest setting possible. Add the grated Asiago cheese in small handfuls, whisking each addition in until it’s fully melted and smooth before adding the next. Never let the sauce boil after you add the cheese!

Combine and Serve

• Turn off the heat. Using a colander, drain your cooked pasta and immediately add it to the skillet with the sauce. Add the sliced rotisserie chicken, the diced tomatoes, and most of the green onions (save some for garnish!). Use tongs to gently toss everything together until every single piece of penne is glistening with that incredible spicy cream sauce. If the sauce seems a tad too thick, splash in a little of that reserved starchy pasta water until it’s perfect.
• Stir in the fresh, chopped basil. The residual heat will wilt it just enough to release its sweet aroma. Divide the pasta among warm bowls, garnish with the remaining green onions, and get ready for the compliments to roll in.