I'm not much of a vegetable lover, but I do think this is delicious.
Why is the liquid refusing to reduce? Zucchini contains approximately ninety-five percent water by weight, meaning salt-free cellular structures release massive volumes of moisture upon initial heating. Combat this deluge by maintaining a medium-high flame to flash-evaporate excess moisture before adding canned tomatoes. Canned tomatoes, historically preserved to extend the seasonal harvest of southern Italy and the Americas beyond the frost line, bring inherent acidity that counters the neutral profile of squash. Cooking these ingredients down requires broad surface area, so deploy a twelve-inch skillet if available; narrow saucepans trap steam and prolong cooking times. Should sticking occur without added fats, reserve broth or tomato juices in a squeeze bottle to apply precisely one tablespoon at a time. Zucchini reaches doneness when translucent around the edges yet retaining slight central resistance, typically occurring within eight to ten minutes of sautéing. Residual pan heat suffices for melting dairy, so extinguishing burners immediately after covering the skillet prevents cheddar proteins from seizing into rubbery clumps. Rest the covered pan for precisely ten minutes before stirring the contents. Sharp cheddar contains lower moisture content than fresh mozzarella, yielding a stable emulsion when integrated into the reduced tomato paste. Stirring too early breaks this fat emulsion, resulting in oil separation rather than a cohesive sauce.