Place the almond flour, erythritol, and Egg White Protein in the work bowl of the food processor and process on low speed until they are fully combined and the grind is very fine.
Add the almond extract. With the food processor running, slowly pour in two tablespoons of warm water.
Add the remaining tablespoon of water a drop at a time until the marzipan comes together and starts to form a ball in the work bowl.
When it comes together, turn it out onto a clean counter and knead it by hand until it is soft and supple. If it is too sticky, dust the counter with a little powdered erythritol.
Roll it into a log and wrap it tightly in plastic wrap.
Place in the refrigerator to chill for at least an hour until it feels firm to the touch.
Once the marzipan has been chilled, it can be colored with gel or paste food colorings (liquid food coloring will make the texture too loose), molded into candies and decorations, or rolled out to cover cakes and cupcakes.
Store marzipan tightly wrapped in plastic wrap in the refrigerator for two weeks, or in the freezer for up to three months.