First, you're going to make a roux. Place a medium saucepan on the stove. Add the butter and turn the heat to medium heat. Begin to melt the butter, taking care not to brown it.

Add the garlic and stir.

Once the butter is completely melted, add the flour. Use a whisk to mix together the flour and butter. Whisk together until a paste is formed.

Keep stirring so that the flour begins to cook, but not burn. You’ll be able to tell that the roux is done cooking when it starts to develop a nutty flavor.

Gradually pour in the milk, whisking as you pour it in.

Bring the milk mixture to a simmer.

Season with salt, black pepper, and nutmeg.

Use the sauce immediately for best results.