In a large heavy skillet, heat the olive oil over low heat. Add the garlic, red pepper flakes, salt and black pepper and cook about 2 minutes, stirring occasionally, until the garlic is tender but not browned.

Increase heat to medium and add shrimp and sauté, turning the shrimp once with tongs, until shrimp are just cooked through, about 2 minutes each side. Set aside.

Mash the avocado and mix with the lime juice and cilantro in a bowl. Season with salt.

To assemble: Spread avocado mixture on the Ritz crackers. Top with shrimp and cheese.