Beat 13T room temp butter until soft and smooth.
Add 1c sugar and beat til creamy.
Add 1 egg + 1 egg yolk -- beat until well incorporated.
Mix in 1t vanilla.
Then add and mix just until incorporated:
2 1/2c flour,
1t baking powder,
pinch of salt.
Gather dough into a ball, divide in half, pat each part into a disk
and wrap in plastic.
Chill for 15-30min.
Butter a 9" springform pan and place on a cookie sheet.
Roll one disk of dough to a 9" circle and place in pan -- or squish in--pan to size with fingers.
Spread about 2c of a good chunky jam/preserve over dough (I pulled a
jar of blueberry out of my pantry).
Roll the other disk to a 9" circle (easiest on a wax paper sheet so
that you can easily lift onto jam) -- place in pan and use fingers to
even if necessary to make sure it covers the jam.
Lightly brush with water and sprinkle with 2T sugar -- I have large
grained raw sugar that was very pretty on top.