Preheat the oven to 350 F (180 c) oven.
In a large bowl or in a stand mixer, combine the flour, sugar, salt and baking powder.
Add the eggs, one at a time followed by the Vin Santo. At first, it should look very crumbly, almost like a thick cornmeal. Once you start working it with your hands it will come together.
Turn the dough out onto a clean surface and knead lightly with your hands until the dough comes together. If the dough is too dry and doesn’t come together into a ball add a teaspoon of water at a time until it does.
Add the almonds and continue to knead until they are well incorporated into the dough. Keep in mind that it’s perfectly normal for the almonds to fall out as you start to work them in - just stuff them back into the side of the dough and keep kneading. Sometimes not all the almonds make it in because the dough is a bit dryer (depends on egg size and flour brand) and that’s perfectly fine.
Dust your work surface lightly with flour (if the dough is sticking) and roll the dough into two logs about ¾ inch (2 cm) high and 1 ½ inch (4 cm) wide, slightly pressing them down on the top so they are slightly flattened.
Arrange logs on a baking sheet at least 2-3 inches (5-8 cm) apart.
Beat the remaining egg yolk with ½ teaspoon of water and brush all over the top and sides of the logs.
Bake for 20-25 minutes until lightly brown.
Remove and let cool for about 10 minutes. Cut into slices with a sharp knife slightly on the bias about ½ inch (1.5 cm).
Return the cantuccini cut side up to the baking sheet and bake again for 10-15 minutes, checking to be sure they don’t burn on the bottom. When you take them out, they will still be soft but as they cool they will harden up.
Transfer to a wire rack to cool.