Combine fresh or frozen cranberries with sugar and water in a saucepan. Bring to a boil, then simmer for 10-15 minutes until cranberries burst and break down into a thick sauce.

Preheat oven to 325°F (163°C). Line a 9-inch square baking dish with parchment paper.

In a mixing bowl, combine melted butter, granulated sugar, and vanilla extract until creamy. Add all-purpose flour and a pinch of salt, mixing until crumbly. Press into the prepared baking dish and bake for 16-18 minutes.

Whisk together granulated sugar, flour, eggs, and lemon juice in a bowl until smooth. Set aside.

Once the crust has cooled, pour the cranberry filling evenly over it. Refrigerate for 45 minutes.

Pour the lemon filling over the set cranberry layer. Bake at 350°F (177°C) for 43-45 minutes, until the filling is set and edges are slightly puffed.

Cool the baking dish on a wire rack for at least 30 minutes, then chill in the refrigerator for 1-2 hours.

Lift the bars from the pan using the parchment overhang and cut into squares. Dust with powdered sugar before serving.