Position rack in center of oven and preheat to 350°F. Line baking sheet with parchment paper. Sift flour, baking powder and salt into medium bowl. Mix sugar, melted butter, 3 eggs, vanilla extract, and orange zest in a large bowl. Add flour mixture to the egg mixture and stir with a spatula until almost combined; add almonds and stir just until well blended.

Divide the dough in half. Using floured hands, shape each dough half into 2 1/2-inch wide log that is about 13" long on the prepared baking sheet. If you like, brush a bit of beaten egg over the top of each, and/0r sprinkle them with coarse sugar.

Bake for 30 minutes, until golden and set. Cool completely on a wire rack. while you reduce the oven temperature to 250F.  When cool enough to handle, slice the logs on a slight diagonal into 1/2" slices; arrange upright on a baking sheet, allowing room for the air to circulate around them. Bake for another half hour; if you like, turn the oven off and leave them inside to firm up as they cool down.