Heat oven to 350F. Grease a 9″ springform pan with butter and dust with flour.
Peel and dice apples (about 1/2″ dice) and toss with lemon juice. Set aside.
Place remaining streusel ingredients (except pecans) in a food processor. Add butter and shortening. Pulse about 10 times then process for 5 to 10 seconds until there are no visible lumps of fat.
Mix together 1 3/4 cups flour, baking powder, soda and salt in a medium bowl.
Using an electric hand mixer or the paddle attachment on a stand mixer beat 1/2 cup butter for about 30 seconds, then beat in granulated sugar and vanilla. Add eggs, one at a time, beating well after each addition. Alternately add flour mixture and ricotta cheese to batter. Mix on low speed after each addition until combined. Note: this batter will be rather thick and stiff.
Spread 1/2 of the batter into the bottom of the pan. Sprinkle with 1/2 of the filling mixture and then the diced apples. Spoon remaining batter over apples. It will not spread smoothly so be gentle and use dollops of batter. Sprinkle with remaining topping and nuts.
Bake 45-50 minutes more or until a wooden toothpick inserted in the center comes out clean. Cool at least 1 hour on a wire rack.