Preheat your oven to 375°.
Roll your pie crust out on a lightly floured surface to 1/8" thick. Using a large glass or round cookie cutter, cut out as many 4"-5" circles as possible. (It will likely yield 13-15) Place the pie crust rounds on a non-stick cookie sheet and refrigerate while you prepare the apples and butter.
In a small saucepan, over medium heat, cook the butter for 4-5 minutes until browned. (Watch closely because it quickly goes from browned to burnt!) Once browned, immediately remove from the heat.
Cut the apples into very thin slices and add them to a medium bowl. Toss with the lemon juice so they don't brown. Add the browned butter to the bowl and toss until all of the apple slices are well coated.
Arrange the apple slices in a rosette pattern over each pie crust round. Top each tart with 1 teaspoon pecans. In a small bowl, mix the sugar, cinnamon and salt. Sprinkle the top of each tart with 1/2 teaspoon of the cinnamon sugar mixture. Bake at 375° for 35 minutes, or until the pie crusts are golden brown. Allow to cool to room temperature and store in an airtight container for up to 12 hours or refrigerated for any longer.