How to Make It
Prepare Filling: Bring first 4 ingredients to a light boil in a Dutch oven over medium-high heat. Reduce heat to medium-low, and simmer, stirring often, 25 to 30 minutes or until apples are tender and juices thicken. Discard lemon slices. Cool completely (about 2 hours). Cover and chill until ready to use.
Prepare Cake: Lightly grease disposable cake pans with cooking spray; line bottoms of pans with parchment paper, and lightly grease parchment paper.
Preheat oven to 350°. Beat butter at medium speed with a heavy-duty electric stand mixer until creamy. Gradually add sugar, beating until light and fluffy. Add egg yolks, 1 at a time, beating just until blended after each addition.
Stir together apple pie spice and 2 3/4 cups flour in a medium bowl; stir together buttermilk and baking soda in a small bowl. Add flour mixture to butter mixture alternately with buttermilk mixture, beginning and ending with flour mixture. Beat at low speed just until blended after each addition.
Stir together pecans and remaining 1/4 cup flour. Fold pecan mixture and apple butter into batter.
Beat egg whites at high speed with an electric mixer until stiff peaks form. Stir about one-third of egg whites into batter; fold in remaining egg whites.
Divide cake batter among prepared pans, spreading with an offset spatula.
Bake at 350° for 7 minutes; rotate pans from top rack to bottom rack. Bake 7 to 9 more minutes or until a wooden pick inserted in center comes out clean.
Remove cake layers from oven, and brush each with 2 to 3 Tbsp. warm Apple Cider Glaze. (Reserve remaining glaze.) Cool cake layers in pans on wire racks 10 minutes. Remove from pans to wire racks; discard parchment paper. Cool completely (about 30 minutes).
Assemble Cake: Place 1 layer, glaze-side up, on serving platter. Top with 1 1/2 cups filling. Repeat with remaining layers and filling. Top last layer with any remaining filling, and drizzle cake with desired amount of reserved Apple Cider Glaze.