Dough: stir a pinch of sugar into warm milk and sprinkle in yeast. Let it stand 50 minutes or so until the top gets frothy. Stir very easily to pick up any dry grains on the top. Sift flour and 1/4 cup sugar into a large bowl. Melt 4 tablespoons of the butter and cool slightly. Grease a baking sheet. Gently beat the melted butter, egg and lemon peel into yeast mixture. Make a hole in the flour, pour yeast mixture into it. Mix to make a dough. Knead dough on a floured board. Spread dough on baking sheet. Cover and let rise in warm place until doubled or at least 1 1/2 hours.

Preheat oven to 400f. Melt remaining butter, mix with remaining sugar and almonds in a small bowl. Stir in cold milk; cool. Spread cooled mixture of dough after it has risen. Bake 40 minutes or until top is golden brown. Watch it very carefully when it gets to finishing time as it burns very quickly. Cool on baking sheet and then cut into bars.

Filling: cream butter, powdered sugar and vanilla in a small bowl until light and fluffy. Split each bar in half horizontally. Spread the filling on one piece on the cut side, place another piece with cut down on the filling so topping Is on top.

I found this very time consuming. I cut the sheet cake horizontally while it was whole. Then put on filling, and then put the top on and cut into bars. Also, butter filling is soft, so cake should be chilled before cutting into bars if you do it all at one time otherwise the filling squeezes out as you cut.