In a bowl, sift together the flour, baking powder, cinnamon, and salt. Set aside.
I a food processor, pulse together the almond paste and sugar until smooth.
Add butter, sugar and egg. Pulse until smooth.
Add flour mixture and pulse until dough is formed.
Dived dough into 4 equal parts, wrap each part with plastic wrap and let rest in the refrigerator for about 30 minutes.
Preheat oven to 350F, line a cookie sheet with parchment paper.
On a clean and smooth surface sprinkle some flour, roll each part into 10" log.
Transfer logs to a lined baking sheet and flatten to about 2".
Bake for 12-15 minutes, just until dry.
Using the back of a wooden spoon, make a trench down the center of each log. Return to oven for 8-10 minutes longer. Or until golden brown.
Remove from the oven and let cool.
In a small bowl, whisk together the confectionery sugar and milk until smooth.
Drizzle glaze over logs. Once the glaze hardens cut the logs into 2" wide cookies.