Toast the whole almonds on a baking sheet until they smell toasty and start to turn golden, about 10 minutes. Cool, then pulse in a food processor until they form fine crumbs.

Whisk together the almond meal, baking powder, salt and flour in a bowl until blended.

Pulse almond paste, sugar and butter in food processor until smooth. Add the eggs and pulse again to blend. Add the flour mixture and pulse a few times, just until the dough comes together. Dump onto a lightly floured surface and pat into a disc. Wrap dough in plastic and chill 1 hour.

On a lightly floured surface, divide dough into 4 pieces. Use your hands to roll each piece into logs about 8 inches long.

Arrange the logs on one or two rimmed baking sheets lined with parchment, spacing 3 inches apart. Bake 12  minutes.

Lay the handle of a wooden spoon lengthwise along each log, pressing down to form a trench. If using amaretto, stir into the jam. Spoon jam evenly into trench. Return cookies to the oven and bake an additional 20 - 25 minutes, until the edges turn lightly golden and the cookies are feel firm to the touch. Sprinkle the tops with the sliced almonds, and transfer to a rack to cool.

With a large sharp knife, cut the logs on the diagonal into slices.