For the bacon: Preheat the oven to 350 degrees F. Line a rimmed baking sheet with foil and place a rack over it. Arrange the bacon strips on the rack so they are not overlapping. Stir the maple syrup and brown sugar together in a small bowl. Brush both sides of the bacon with the maple mixture and bake until crisp and caramelized, 25 to 30 minutes. Let cool slightly on the rack, loosen from the rack, then cool completely. Finely chop 4 slices of the bacon; set the remaining slices aside for garnish.
For the cupcakes: Set the ice-cream cones into the cups of 2 muffin tins. Prepare the cake mix according to package instructions, adding the maple extract and finely chopped bacon after the batter is combined. Pour the batter into a small pitcher (work in batches if necessary) and fill each cone so that batter comes 1/4 inch below the top cupped portion. Bake until the cake rises above the edges of the cones and a tester inserted in the center of one comes out clean, about 20 minutes. Cool completely.
For the buttercream: Beat the butter on high speed in a mixer fitted with the paddle attachment until light and fluffy, 30 seconds to 1 minute. Reduce the speed to low and add the confectioners' sugar. Beat until the sugar is incorporated, then increase the speed to high and until light and fluffy, scraping down the sides of the bowl as needed. Beat in the maple syrup and salt. Mix on low until combined, then gradually increase speed to medium high. Add milk a tablespoon at a time to make a smooth, pipeable frosting. Beat on high until very smooth and fluffy, about 2 minutes.
Put the buttercream in a pastry bag fitted with a large star tip and pipe spiral swirls on top of the cupcakes (to resemble soft-serve ice cream). Break the 6 remaining slices of maple bacon into large chunks and stick a chunk into the top of each cupcake.