Beat first 6 ingredients at medium speed with an electric mixer 2 to 3 minutes or until well blended.
Melt butter in a 12-inch ovenproof skillet; add egg mixture.
Bake at 350º for 15 minutes. Remove from oven; sprinkle with tomatoes, cheese, and basil. Return to oven, and bake 15 to 20 more minutes or until set. Garnish, if desired; serve immediately.
Note: Farmer cheese is a mild, part-skim, semisoft cheese available in 8-ounce rounds. Havarti or Monterey Jack cheese may be substituted.
Spinach, Cheddar, and Bacon Omelet: Substitute 1 (10-ounce) package frozen, thawed, and well-drained chopped spinach for thyme. Omit farmer cheese and fresh basil. Top with 8 ounces shredded Cheddar cheese and 1/2 cup cooked, crumbled bacon.