Melt the butter in a saucepan over medium-low heat.
Whisk in the flour and cook for about 1 minute. Skip this step is you are using cornstarch.
Add the garlic and cook for 30 seconds, or until fragrant.
Slowly whisk in the half-and-half until smooth. If using cornstarch, you can make a slurry with some of the half-and-half before adding it in to prevent clumping.
Add the steak seasoning and parmesan cheese.
Simmer until the sauce lightly coats a spoon.
Stir in the frozen corn & turn the heat to simmer. The frozen corn and sauce will get very thick at first. But, the sauce will loosen again once the corn melts.
Cook until the corn is hot: Cook for 5–6 minutes, until the corn is hot and the sauce coats the kernels. Finish with sugar and salt, black pepper to taste.
Notes
Add the corn straight from frozen: No thawing needed.
Expect the sauce to thicken at first: It will loosen again as the frozen corn heats.
Using cornstarch: Skip the flour roux. Whisk the cornstarch into the half-and-half until smooth, then add it to the pan and cook until the sauce lightly thickens.
Keep the heat low: This helps the half-and-half and Parmesan stay smooth.
If the sauce is too thick: Stir in a splash of half-and-half.
Taste before adding salt: Parmesan and seasoning blends may already add enough.
For simpler seasoning: Skip the seasoning blend and use salt and black pepper to taste.