Preheat oven to 325° F (300° F convection). Mix butter and sugars together until light and fluffy -- approximately 2-3 minutes with a mixer.
Add applesauce (or eggs).
Grind almonds to make almond meal, then measure out to add to dry ingredients; whisk to integrate them together.
Stir into sugar mixture until smooth. Fold in sliced almonds and diced crystallized ginger, if using (optional, but highly recommended!).
Roll dough ball in a light dusting of gfJules Flour just so it's not too sticky to handle.
Divide dough in half and place on a parchment lined baking sheet. Dust the tops of each mound of dough and your hands with more gfJules Flour, if needed because it's sticky. Pat gently to form into two wide logs, approximately 1 1/4 inches high and 3-4 inches wide. Sprinkle the top with cinnamon-sugar mixture, if desired.
Bake for 35 minutes until browning on the edges and no longer so soft. Remove to cool on a wire rack.
Once cooled, use a serrated knife to cut each log across the wide side into half-inch wide slightly diagonal slices. Depending on how finely you chopped the ginger, it may be harder to cut through evenly, but it won't affect the taste.
Return to the parchment-lined baking sheet and bake for another 15-20 minutes until golden and slightly crispy. They will get crunchier as they cool.
Once cooled, wrap tightly or store in containers sealed from the air to retain crunchiness. Return to a 200° F oven on a baking sheet for 5 minutes to restore crispness if they absorb moisture in subsequent days.