In a food processor, pulse together the almonds with 1 teaspoon of powdered sugar until very fine in texture.
Transfer the almond mixture to a small bowl and set aside.
In the same processor pulse together the granulated sugar with the mandarin orange zest.
In a large bowl beat together the orange sugar mixture with the egg, orange juice and vanilla extract until combined.
Add in the ground almond mixture, the sifted flour, baking powder, a pinch of salt and stir the mixture until well combined.
In a large heavy pot or a dutch oven, pour in enough oil to reach 2 inches high and heat to 350 degrees F. Preferable using a candy thermometer for accuracy.
Use a 1 1/2 inch cookie scoop or 2 small spoons to drop bits of dough into the hot oil. Don't overcrowd the fritters.
Fry the fritters for about 1 1/2 minutes turning often with a slotted spoon until they are puffed up and have an all around golden brown colour in appearance.
Use a slotted spoon to remove the fritters from the pot and allow to drain on a paper lined cookie sheet.
Repeat with the remaining batter.
When finished frying the remaining frittelle, dust the fritters with powdered sugar and serve while still warm.