Makes 12 large squares
1 pound pitted dried dates, chopped
1 cup water
1 cup sugar
1/2 cup freshly squeezed lemon juice
3 cups rolled oats
2 1/2 cups all-purpose flour
1 3/4 cups packed brown sugar
3/4 teaspoon baking soda
3/4 teaspoon salt
1 3/4 cups (3 1/2 sticks) unsalted butter, melted
Preheat oven to 350 degrees F. Generously butter a 9- x 12-inch pan.
Combine dates and water in a saucepan. Cook at a low boil for 5 minutes, until mixture is as thick as mashed potatoes. Stir in sugar and remove from heat. Add lemon juice and set aside to cool.
In a large bowl, mix together oats, flour, brown sugar, baking soda, and salt. Add melted butter to dry mixture. Stir to evenly moisten.
Spread half oat mixture in baking pan to form an even layer. Cover evenly with all date mixture. Spread remaining oat mixture over top.
Bake about 40 minutes, until top is golden brown and pebbly. The edges should start caramelizing. Set aside to cool, in pan on rack, about 1 hour. Run a sharp knife along inside edges to loosen. Invert, trim edges, and cut into squares.