Pour in a large bowl the flour with water, salt, olive oil, baking powder and a wine glass of vinegar. Knead all together. Separate the dough into two parts and let rest for 1 hour and rise. Separate into two parts and roll out a sheet. Place one sheet on the bottom of the pan and brush with butter. Put the milk and butter in a pan and boil. With a mixer, beat the sugar with the egg and lemon and boil until it thickens. Pour the cream into the pan and cover with the second sheet. Beat the egg with a little milk. Carefully cut the bougatsa in squares so the cream doesn’t overflow the dough. Brush with egg and milk mixture.