Rory's Guaranteed Rise Sourdough Cinnamon Rolls
1 (4 ounce) package softened cream cheese 1 cup brown sugar, or more to taste 1 cup fed sourdough starter 1 egg, at room temperature 1 teaspoon instant yeast 1 teaspoon vanilla extract 3 tablespoons ground cinnamon 4 cups all-purpose flour ¼ cup softened butter ½ cup butter, melted and cooled ½ pound confectioners' sugar ½ teaspoon salt ¾ cup lukewarm milk ¾ cup white sugar