Mix together half-and-half, cornstarch, sugar, salt, pepper, and red pepper flakes in a 6-quart slow cooker.: The aroma will be faint initially, mostly of sweet dairy and spices blending together, and you should notice the cornstarch mixing into the half and half without lumps if you whisk well. This stage matters because even dispersion prevents grainy pockets later, and the sugar and salt dissolve now to season evenly. A common mistake is not fully dissolving the cornstarch, which can leave small thickened clumps that become more noticeable as it cooks, so take the time to stir until smooth.
Add butter, cream cheese, and frozen corn. Mix together.: As you add the softened pieces of butter and cubed cream cheese , they will sit on top of the cold corn at first. Pressing them gently into the mix and stirring ensures the cheese begins to soften. You will see the surfaces of the cheese soften and the butter start to gloss; this is important because it jumpstarts the emulsion that will give the sauce its silk. Avoid adding ingredients and then leaving them unmixed, because pockets of unmelted cheese can create uneven texture later.
Cover and cook on LOW for 4 hours, stirring a few times during that time. It will thicken more as it cools.: The scent shifts to a warm, dairy sweetness as the cooker warms. Slow, steady heat lets the cream and cheese melt gently without breaking, producing a smooth, cohesive sauce while the corn releases starches that meld into the mixture. Stirring a few times helps distribute heat and prevents a film from forming on the surface. One frequent error is opening the lid too often, which can drop temperature and extend cooking time; limit stirs to the stated few times.
It will thicken more as it cools: The true test comes after the dish rests. The sauce tightens and clings to the corn , giving that comforting creaminess. You will notice a glossy, slightly denser texture and the aromas deepen into a richer, more concentrated dairy note. Expect a different mouthfeel when hot versus warm; if it seems thin while hot, remember that cooling will naturally thicken it. A misstep is serving immediately without allowing a short rest, which can lead to a looser texture than intended.
