In a heavy, large saucepan, bring chicken stock to a boil. Add grits gradually, in a constant slow stream and whisk continually. Reduce the heat to a low simmer and stir frequently until water is almost absorbed, about 15 minutes.
Stir in the milk and simmer, while still stirring occasionally, for 30 minutes. Add roasted garlic and season with salt and pepper. Serve immediately.
Preheat oven to 300 degrees F.
Break apart the garlic cloves and remove the outer paper but leave on the skin. Toss in a baking pan with olive oil. Roast in oven for 30 minutes. Remove from oven and let cool. Squeeze garlic clove out of the skin.