Cook the 8 ounces penne pasta according to the package directions until al dente. Drain the pasta, reserving 1 cup of the pasta water, and set both aside.: As the water boils, you will hear a steady vigorous bubble and smell the wheat of the penne pasta releasing steam. Aim for al dente so the pasta holds structure when tossed in sauce, it should be tender with a slight bite. When you drain, reserve a cup of that cloudy water because its starch will act like glue, making the sauce cling to every tube. A common mistake is overcooking the pasta, which leads to a mushy texture once combined with the rich sauce, so start checking a minute or two before the package suggests.
Heat the 2 tablespoons olive oil in a large pan over medium-high heat. Add the 1 tablespoon minced garlic to the pan and cook for 1 minute, until fragrant.: You will see the olive oil shimmer and then the minced garlic will sizzle softly, releasing a warm, aromatic perfume. Keep the garlic moving so it browns lightly rather than burning, because burned garlic tastes bitter. This step builds a flavor base, the oil carrying the garlic aromas into the sauce. If the garlic darkens too quickly, reduce the heat immediately to avoid bitterness.
Slowly whisk the 1 cup reserved pasta water into the oil and garlic. Add 1 cup ricotta cheese and 1 cup heavy cream to the liquid, then reduce the heat to medium-low. Stir until the ricotta is melted and the sauce is smooth.: You will notice the liquid change from clear to slightly milky as starch disperses, and the whisking encourages an even suspension. Adding ricotta cheese and heavy cream straight into this warm mix helps them meld without scorching. Lowering the heat is critical so the dairy warms gently and combines into a smooth base rather than separating. The common error here is adding cold dairy to very high heat, which can cause curdling, so aim for gentle warmth.
Add in the 1/2 cup freshly shredded Parmesan cheese, 1/2 cup freshly shredded mozzarella cheese, 1/2 cup freshly shredded Asiago cheese, and salt and pepper to taste. Reduce the heat to low and whisk the sauce until all the cheese is melted and the sauce is creamy and smooth.: As you stir, watch the texture evolve from grainy to velvety, and take in the soft dairy scent as the ricotta cheese integrates. The motion should be steady, coaxing the curds to dissolve into the cream, and you may notice the sauce thickening slightly. If you see lumps, continue stirring over gentle heat and use a whisk to encourage homogenization. A frequent pitfall is impatience, ramping the heat up, which risks breaking the emulsion.
Add in the cooked pasta and stir to coat it in the cheese sauce. Remove the pasta from the heat and serve fresh with additional cheese as garnish.: The cheeses will melt at different rates, so give them time to incorporate and watch for a glossy sheen that indicates a successful emulsion. You will hear a soft, near silent merging as the cheeses relax into the cream, and the aroma becomes richer and more complex. If the sauce appears grainy, it may be too hot or the cheese was added too fast; reduce heat and whisk patiently. Over seasoning is easy at this point because the Parmesan cheese and Asiago cheese are salty, so taste before adding extra salt.
Add in the cooked pasta and stir to coat it in the cheese sauce. Remove the pasta from the heat and serve fresh with additional cheese as garnish: When the penne pasta meets the sauce, you should see ribbons of creamy sauce clinging to each piece, and a gentle steam will rise as you toss. The tactile sensation should be creamy yet structured, not soupy. Tossing off heat preserves a glossy finish and prevents the sauce from tightening or separating. A typical misstep is leaving the pasta on residual high heat so the sauce becomes thick and pasty, so remove from heat and serve promptly for the best texture.