Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone mat.
Mix the dry ingredients: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
Cream the butter and sugar: In a large bowl, beat the softened butter and sugar together until light and fluffy (about 2-3 minutes). You can use a hand mixer or stand mixer for this.
Add eggs and extracts: Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla and almond extracts (and orange zest, if using).
Combine dry ingredients: Gradually add the dry flour mixture to the wet ingredients, mixing until just combined.
Fold in the add-ins: Stir in the dried cherries and sliced almonds, being careful not to over-mix.
Shape the dough: Divide the dough in half and shape each half into a log about 10 inches long and 2 inches wide. Place the logs on the prepared baking sheet, spacing them apart.
First bake: Bake the biscotti logs for 25-30 minutes, or until they are golden brown and firm to the touch. They will puff up a little and become slightly cracked on top.
Cool slightly, slice, and bake again: Allow the logs to cool on the sheet for 10 minutes. Then, carefully transfer them to a cutting board and slice diagonally into 1/2-inch thick pieces using a serrated knife.
Second bake: Lay the slices cut-side down on the baking sheet and bake for an additional 10-15 minutes, flipping halfway through, until they are dry and crisp.
Cool completely: Let the biscotti cool completely on a wire rack before serving. They will crisp up as they cool.