Combine all the ingredients in a cooking pot.

Bring the mixture to a boil over medium heat and cook for around 20-25 minutes, stirring occasionally. To check for doneness, coat a spoon with the jam and quickly trace a line across the back of it with your fingertip.

Pour the hot jam into a clean bowl, cover with plastic wrap, and freeze until cold but not frozen.

In a bowl, combine the flour, almond flour, and salt.

In another bowl, add the powdered sugar, butter, and vanilla. Beat with a hand mixer just until well combined and creamy. Do not beat until fluffy.

Add the egg and beat until fully incorporated.

Add the dry ingredients and beat until just combined. Wrap the dough in plastic wrap and freeze for 30 minutes, or until it is well chilled but still pliable. Alternatively, refrigerate overnight.

Place the rounds without holes onto baking sheets lined with parchment paper. The cookies will not spread much, so they do not need to be placed far apart.

Spoon or pipe the strawberry jam, no more than 1 tablespoon per cookie, into the center of each dough round. Place the dough rounds with windows on top, then gently pinch or press around the edges to seal the top and bottom together. Do not press in the center so the jam stays in place.

Place the baking trays in the fridge while the oven is preheating to 355F (180C).

Bake in batches for about 12 minutes, or until the edges start to turn lightly golden. The cookies themselves should stay pale.

Allow the cookies to rest on the baking sheet for 5–10 minutes before transferring them to a wire rack to cool completely.