Preheat oven to 350. Grease and flour a 9 x 9 square cake pan or a 9-inch round cake pan with removable bottom.
Add the apple pieces and slices into a small bowl and squeeze the lemon juice over it; set aside.
In a medium skillet, add the apples, lemon juice, sugar, cinnamon, ginger and jam. Stir together.
Sauté on medium heat for about 5-7 minutes. The apples are ready when they are soft to touch when you poke with a fork.
Set the pan aside and let it cool for a few minutes while you prep the other ingredients.
In a large bowl, sift together the flour, baking powder and salt. Toss in the lemon zest and with your hands, mix it into the flour mixture to release the lemon essence.
In a large bowl with an electric mixer, beat the sugar and eggs until creamy (about 5 minutes)You could beat this by hand with a wooden spoon. Beat in the oil and the sourdough discard. Mix well, stopping mixer to scrape sides of bowl to incorporate.
Add flour mixture into the sourdough mixture a half up at a time. Scrape down the sides of the bowl with spatula and mix well after every addition.
Pour the batter into prepared pan. Arrange the apple slices and the juices from pan over the batter.
Sprinkle the turbinado sugar, thin pats of butter, and the almond slices on top of the cake. 2 Tablespoons turbinado sugar. Bake about 50-60 minutes, or until skewer inserted in the center comes out clean. Check cake at about 40 minutes. Every oven is different. If cake is browning, cover with aluminum foil for remainder of baking time.
Let cool for about 20 minutes before removing from cake pan. Best served warm.