Preheat the oven to 350°.
Put the 1½ tablespoons of flour into a small bowl. Toss in the dates and walnuts and coat them well with the flour to prevent them from sinking to the bottom of the pan. Set aside.
Line a 9-inch square pan with aluminum foil, extending the foil over the edges of the pan for easy lifting later. Use a non-stick baking spray to spray the bottom and sides of the foil. Alternatively, you can butter the foil on the bottom and up the sides of the pan, then dust it with flour. Set aside.
Into a small bowl, sift the ½ cup of flour, baking powder, and salt together. Set aside.
In a large bowl, beat the eggs until foamy. Gradually add the sugar and vanilla extract until blended.
Fold in the flour mixture and then fold in the coated dates and walnuts.
Spread the batter evenly into the prepared pan.
Bake at 350° for 15-25 minutes, or until golden brown on top and firm to the touch.
Cool completely on a wire rack. Lift the edges of the aluminum foil and place the date nut bars onto a board to cut into squares. Dust the tops of the bars with confectioner's sugar.
Store the dates covered at room temperature.