Slice the chicken into 1 to 1.5 inch pieces while it’s at room temp around 70°F. Sprinkle salt, pepper, and Italian seasoning evenly, then use your hands to toss and lightly press it in so it sticks. Let it sit for 5 minutes. You’ll notice the surface turns slightly glossy and speckled. That’s your cue it’s ready. Skip the 5 minute rest and the seasoning won’t hold, and later the chicken tastes flat.

Heat olive oil over medium heat, about 6 out of 10, for 2 minutes until it shimmers. Add the chicken in a single layer and don’t touch it for 3 to 4 minutes. Then flip each piece with tongs and cook another 3 to 4 minutes. You should hear a steady sizzle and see golden edges forming. That color matters. Move it too early and you lose browning, and the final sauce won’t have as much depth.

Lower the heat to medium-low, about 4 out of 10. Add butter and garlic, then stir constantly for 60 to 90 seconds until the garlic smells soft and mellow. Pour in the broth, milk, and cream, then add the penne. Use a spoon to press the pasta down so it’s mostly under the liquid. The mixture should look pale and slightly cloudy. If pieces stick out, they cook unevenly and stay firm in spots.

Bring everything to a gentle simmer around 190°F and keep it there for 10 to 12 minutes. Stir every 2 to 3 minutes using a slow circular motion so nothing sticks. Keep the lid slightly open to control the heat. You’ll see the sauce thicken and cling to the pasta. The penne should feel tender but not mushy. Go past 12 minutes and the bottom starts to stick and the sauce turns too thick. (I used to walk away here, and it always caught on the bottom.)

Turn the heat down to low, about 2 out of 10. Add parmesan in small handfuls over 2 to 3 minutes, folding it in with a gentle scoop motion instead of stirring fast. Watch for the sauce to turn glossy and slightly stretchy. It should coat the back of a spoon. Add it too fast or over higher heat and it clumps instead of melting smooth.

Let the pasta rest off heat for 2 minutes so the sauce settles to about 150°F. Spoon onto plates and sprinkle parsley over the top using your fingers. The sauce should cling and look creamy, not runny. The parsley stays bright green. Wait too long and the sauce tightens up and loses that smooth finish.