Preheat the oven to 375F. Line a rectangular or square pan with parchment paper and set aside.
Place the flour, oats, sugar, salt, butter, baking powder, vanilla and yogurt in a large bowl and mix until you get a crumbly dough. Reserve 1/3 of this mixture.
Transfer the rest to the baking pan and gently press it on the bottom.
Bake for about 8 minutes until slightly golden. Let it cool for a bit.
Spread the jam over the crust. Top with the remaining crumble.
Take the pan back to the oven and bake for another 18-20 minutes. You will see that the top gets golden-brown and the jam is bubbling.
Remove the pan from heat and let it cool completely.
Use the parchment paper to take the cake out of the pan.
Cut it into squares and enjoy!