01 -
Warm up your oven to 350°F. Put parchment sheets crisscross in your 8x8 pan with extra paper hanging over the sides.
02 -
Melt the butter, then add brown sugar, baking powder, and salt. Mix in the oats and flour. Set aside 1 cup for the top layer.
03 -
Push the rest of the mixture into your lined pan. Pop it in the oven until it turns golden, about 12-14 minutes.
04 -
Combine lemon zest, fresh juice, condensed milk, and leftover salt until everything's well blended.
05 -
Spread filling over the warm base, sprinkle with saved crumble. Bake for 22-24 minutes until the edges go brown.
06 -
Let it cool totally (around 90 minutes), maybe chill for half an hour to set. Then cut into 12 pieces.