In 12-inch nonstick skillet, cook sausage over medium heat, stirring frequently, until browned and no longer pink. Remove sausage from skillet; drain on paper towels. Wipe skillet clean with paper towels; set aside. Meanwhile, in medium bowl, lightly beat eggs, 2 tablespoons sour cream, the half-and-half and taco seasoning mix with wire whisk until well blended.
In 10-inch nonstick skillet, melt butter over medium heat. Add egg mixture; cook 2 to 4 minutes, stirring frequently, until mixture is very moist. Stir in cooked sausage, 2 tablespoons chives, 2 tablespoons cilantro, the tomato and chiles. Cook 1 to 2 minutes longer or until egg mixture is set but still moist. Remove from heat.
Place tortillas on work surface. Top half of each tortilla with 2 to 3 tablespoons egg mixture; sprinkle each with 1 tablespoon of each of the cheeses. Fold untopped half of tortillas over egg mixture.
Heat same 12-inch skillet over medium heat. Place 2 quesadillas in skillet; cook 30 to 45 seconds on each side or until crisp and lightly browned. Remove from skillet; place on serving plate. Repeat with remaining quesadillas. With pizza cutter or sharp knife, cut each quesadilla into wedges. Top each serving (2 quesadillas) with about 1/2 tablespoon each of chives, taco sauce and sour cream.