Cava and Chipotle stock have each outperformed the S&P 500 so far this year.Fast casual dining has become one of the most popular options for diners over the last several years.Two leading fast casual restaurant chains are Mediterranean-inspired CAVA Group (CAVA -1.10%) and burrito specialist Chipotle Mexican Grill (CMG 0.21%).So far in 2024, Cava stock is up 98% while shares of Chipotle have gained 25% -- each handily topping the S&P 500.Let's dive into the business results of Cava and Chipotle and assess ...