Make the thumbprint cookies:

1. Use a stand mixer (or hand mixer) and cream the butter and sugar together in a mixing bowl on medium speed until light and fluffy, about 2-3 minutes.
2. Add vanilla and salt, and continue to beat on medium until fully incorporated.
3. Gradually add the flour and beat on low speed until just combined, and the mixture has formed a dough.
4. Use your hands to shape the dough into a ball (it will be a little crumbly).
5. Tightly wrap the dough with plastic cling wrap and chill for at least one hour in the refrigerator.
6. Preheat oven to 350 F. Line a large half sheet baking pan with parchment paper or a silicone baking mat.
7. Use a cookie scoop or spoon to take 1 tablespoon of dough at a time, and roll into 1-inch balls. Place on the lined cookie sheet.
8. Make an indentation with your thumb (or the back of a small spoon or measuring spoon) into the centre of each ball. 
9. Use a small spoon to fill the indentation with jam — be careful that you do not overfill the indentations.
10. Place the cookie sheet into refrigerator to chill while the oven preheats.
11. Bake the cookies for 13-15 minutes or until edges are lightly browned. Allow the cookies to cool on the cookie sheet for 5 minutes before carefully transferring to a wire cooling rack to cool completely.

Make the glaze:

1. In a medium mixing bowl, whisk together confectioners' sugar, almond extract and 1 tablespoon of almond milk.
2. Add remaining milk, 1 teaspoon at a time, until you reach the desired consistency. If the mixture is too thick, add more milk. If it is too thin, add more sugar.
3. Using a spoon or a piping bag fitted with a fine round tip to drizzle the glaze over the cooled cookies. Let set for 1-2 hours.