In a bowl, combine the flour, baking powder, salt, and cinnamon.
In a large bowl, mix the oil, sugar, vanilla, and eggs until thick and light yellow.
Combine the wet and dry ingredients and mix well. Fold in the chocolate chips and any dried fruit or nuts.
Cover the dough and refrigerate for 1-2 hours.
Preheat your oven to 350°F (175°C).
Line a baking sheet with parchment paper or a silicone mat.
Shape the dough into three 4-inch wide rectangles, about 1/2 to 3/4 inch high, on the baking sheet. Bake for 20-25 minutes.
Remove from the oven and let cool for 15-20 minutes. Lower the oven temperature to 250°F (120°C).
Slice the mandel bread into 3/4-inch thick pieces. If desired, sprinkle with cinnamon sugar.
Return the slices to the oven and bake for another 15-30 minutes, depending on how crunchy you like them.
Remove from the oven and place on a cooling rack to cool completely. The cookies will harden as they cool.