Chop your onion.
Melt the 3 Tbsp of butter or bacon grease in a skillet over medium heat.
Add the onion and cook until translucent, 3-5 minutes.
Add the flour, salt and pepper and cook, stirring constantly, until the butter starts to take on a little color (3-4 minutes). You are making a roux, and the main thing is to not let it burn.
Add the corn and mix well.
Melt the ½ stick of butter, add to the 1½ cup of milk and whisk together.
Add the milk/butter, sugar and thyme to the corn and mix well.
Simmer until thickened.
Remove from the heat and use an immersion or stick blender to break up ~¼ of the kernels.
Add the parmesan cheese and stir through until melted.
Taste and season more if needed.