Process first 3 ingredients in a food processor until smooth. Add 2 cups cake flour. Process, adding additional flour, 1 tablespoon at a time, as necessary, until dough forms a ball. Shape dough into a 6-inch disk; wrap in wax paper, and chill 50 minutes or until firm but still malleable.
Coat a 10-inch tart pan with removable bottom and 1-inch sides with cooking spray. Remove wax paper from dough, and press into bottom and 1/2 inch up sides of prepared pan.
Bake at 350° for 35 minutes or until golden. Cool in pan on a wire rack 10 minutes; remove from pan, and cool completely. Remove to a serving platter.
Place egg yolks in a small bowl; whisk well. Combine 6 tablespoons granulated sugar, 1/4 cup butter, and lemon juice in a small saucepan. Cook, whisking constantly, over medium-low heat until butter melts. Remove from heat. Gradually whisk about one-fourth of hot mixture into yolks; add to remaining hot mixture, whisking constantly. Place over medium-low heat; cook, whisking constantly, 2 to 3 minutes or just until thickened. Cover lemon curd; cool completely.
Combine pecans and next 3 ingredients in a medium skillet. Place over medium heat; cook, stirring constantly, until sugar melts and mixture is bubbly. Pour in a single layer onto wax paper; cool completely. Carefully remove wax paper, and break into small pieces.
Spread lemon curd in a thin layer over bottom of crust.
Drain peach slices well, and pat dry with a paper towel.
Place preserves in a medium bowl. Microwave at HIGH 20 seconds or just until warm; mash preserves with a fork. Add peach slices, stirring to glaze.
Arrange peach slices in a circular pattern on lemon curd. Gently brush any preserves remaining in bottom of bowl over peach slices. Top peach slices with praline mixture, mounding slightly in center of tart. Garnish, if desired. Serve immediately. Store in refrigerator.
Tip: Select firm, ripe fresh peaches. If using frozen peaches, be sure peaches are completely thawed and well drained. Soft, very ripe peaches produce an undesirable amount of juice on this tart, which interferes with the texture of the lemon curd. Carefully run a thin sharp knife between bottom of pan and pastry to release bottom of pan. Peach jam can be substituted for peach preserves.