Preheat oven to 300°F. Grease 1 ½ quart soufflé dish. Line bottom with wax paper. Beat cream cheese and cheddar cheese in large bowl with an electric mixer until light and fluffy. Beat in eggs one at a time. Mix in mustard and salt, then pour into dish. Put in oven. Bake until you can stick a knife in and it comes out clean. (About an hour) Let cool in shut-off oven for 30 minutes. Remove from oven, cover and refrigerate until cold. Remove from soufflé dish and invert onto a serving plate. Pour salsa over the top. Garnish and serve with crackers.