Preheat oven to 400 F. Arranges bacon strips in large rimmed baking pan. Bake until browned, about 15 minutes. Pour off bacon fat. Brush bacon with half of the syrup. Bake until glazed, about 3 minutes. Flip bacon over, brush the other side and bake until glazed, 3 minutes more. Immediately transfer bacon to a plate to cool completely (bacon will crisp when cooled). Coarsely chop the bacon. (Bacon can be prepared up to 2 hours ahead; do not refrigerate.) 

Tart Crust 

Lightly butter a 9-inch tart pan with a removable bottom. In medium bowl, add flour, brown sugar and salt and stir to combine. Add butter. Using a pastry blender or two knives, cut in butter until mixture resembles coarse meal. Stir in beaten egg to make a soft dough. Firmly and evenly press dough into the tart pan. Freeze for 15 minutes. Preheat oven to 400 F. Place tart on a baking sheet and bake until lightly browned about 10 minutes. Remove from oven. Keep oven on. 

Filling

Drain sweet potatoes, reserving 1/4 cup syrup. Using a food processor, process sweet potatoes until mashed. Add brown sugar, yogurt, flour, ginger, nutmeg, cinnamon and cloves and pulse to combine. Add milk and egg whites and process, scraping down the sides of the bowl, until smooth. Pour into crust. 

Bake for 10 minutes at 400 F. Reduce oven temperature to 350 F. Bake until filling is lightly and evenly puffed and jiggles as a unit when the pan is shaken lightly 45 to 50 minutes. Transfer to wire rack and cool completely. (The tart can be covered and refrigerated for up to 1 day.) 

Caramel Sauce

In a medium heavy saucepan, combine sugar and water. Bring to boil over high heat, stirring constantly. When boiling, stop stirring and cook, occasionally swirling the pan by its handle and washing down any crystals on the sides with a bristle brush dipped in water, until syrup is smoking and the color of an old penny, 3 to 5 minutes. You will not need a candy thermometer—judge the caramel by its color. Reduce heat to low. Carefully and slowly stir in warm cream (it will foam up) and mix until smooth. Remove from heat and stir in vanilla and salt. Let cool. Makes about 3/4 cup sauce. (The sauce can be cooled, covered, and refrigerated for up to 1 day. Reheat before serving.) 

To serve: Remove tart pan sides. Cut into wedges, spoon sauce over each serving and sprinkle with chopped candy bacon.