In a mortar, mash all the marinade ingredients together. Coat the chicken breasts with the mixture and let them sit at room temperature for 1 hour.
Heat a grill or grill pan thoroughly. Wipe it clean with a cloth or brush. Heating the grill makes it easier to clean.

Lightly grease the hot grill with a little oil or fat using a cloth.
Place the chicken breasts on the hot grill and cook until golden brown on both sides.

To make the POLENTA:
In a pot over medium heat, warm the olive oil with 1 tablespoon of butter. Sauté the garlic, onion, green onions, chives, red bell pepper, and parsley.

Add the chicken broth, milk, salt, and pepper. When it is about to boil, slowly add the polenta while whisking constantly to prevent lumps.

Add the remaining 2 tablespoons of butter and the Parmesan cheese. Stir well.
Serve with the grilled chicken breasts.

To make the BECHAMEL SAUCE WITH PEAS:
In a pot, cover the peas with water and bring to a boil. Reduce the heat and simmer until the peas are cooked but still firm. Drain and reserve the cooking liquid.

In another pot over medium heat, warm the oil and melt the butter.
Sauté the garlic and onion.
Add the flour, stirring well into the butter until smooth. Once the flour is lightly golden, gradually add the milk, whisking constantly. Continue whisking to prevent the flour from burning on the bottom. Once it boils, reduce the heat and cook, stirring, for about 5 minutes.

Add the peas and heat through. If the sauce is too thick, add a little of the reserved pea cooking water to reach your desired consistency.
Serve the pea sauce over the chicken breasts and polenta.