1. In large non-stick skillet melt 2 tablespoons of the butter. Add onions. Cook, covered, over medium-low heat for 13 to 15 minutes or until onions are tender, stirring occasionally. Uncover. Cook and stir over medium-high heat for 3 to 5 minutes more or until onions turn light brown. Stir in brown sugar and vinegar. Cook, stirring frequently, for 1 to 3 minutes more or until liquid evaporates. Remove from skillet. Set aside.
2. Meanwhile, wipe skillet out with paper towels. In same large skillet melt the remaining 1 tablespoon butter. Stir in apples and cinnamon. Cook and stir over medium-low heat about 5 minutes or until slightly softened. Remove from heat. Cool at least 30 minutes.
3. In medium bowl stir together apple mixture and cream cheese. Stir in about 3/4 of the onion mixture. Spread on Kellogg's® Town House® Pretzel Flipsides® Original Crackers. Top with the remaining onion mixture.