Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl, cream together the softened butter and sugar until light and fluffy. Add vanilla extract and mix well.
Gradually mix in flour and salt until a soft dough forms.
Roll dough into 1-inch balls and place on the prepared baking sheet. Gently press the center of each with your thumb or the back of a spoon to make a small well.
Fill each well with about 1/2 teaspoon of raspberry jam.
In a small bowl, combine flour and brown sugar. Cut in cold butter with a fork or fingers until the mixture resembles coarse crumbs.
Sprinkle a pinch of crumble over the top of each jam-filled cookie.
Bake for 13–15 minutes, or until the edges are lightly golden.
Let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Notes
Feel free to experiment with different jams or preserves like strawberry or apricot for variety.