Take 1 1/2 cups almond flour and 1 1/2 cups powdered sugar in a food processor and pulse until combined and any lumps are broken up. Add a little almond extract and again pulse to combine. Add 1 egg white or 2 tsp corn syrup and process until a thick dough is formed. If the mass is still too wet and sticky, add more powdered sugar and ground almonds. Keep in mind that it will become firmer after it's been refrigerated.Turn the almond marzipan out onto a work surface and knead it a few times. Form it into a log, wrap it up in plastic wrap and refrigerate.Will keep for at least a month in the refrigerator or up to 6 months in the freezer. Bring to room temperature before using in any recipe.