INSTRUCTIONS
[FOR THE BARS]
1. Adjust oven rack to middle position and heat oven to 325 degrees. Make foil sling for 13 by 9-inch baking pan by folding 2 long sheets of aluminum foil; first sheet should be 13 inches wide and second sheet should be 9 inches wide. Lay sheets of foil in pan perpendicular to each other, with extra foil hanging over edges of pan. Push foil into corners and up sides of pan, smoothing foil flush to pan. Spray foil with vegetable oil spray.
2. Whisk flour, baking soda, and salt together in bowl. Whisk sugar, melted butter, oil, and cream cheese together in second bowl (some lumps of cream cheese will remain but will smooth out later). Add egg and yolk, lemon zest and juice, and vanilla to sugar mixture and whisk until smooth. Add flour mixture and mix with rubber spatula until just combined.
3. Transfer batter to prepared pan, smoothing top with spatula. Bake until light golden brown and toothpick inserted in center comes out clean, 33 to 38 minutes. Let bars cool completely in pan on wire rack, about 2 hours.
[FOR THE GLAZE]
4. Once bars are cooled, whisk lemon juice and cream cheese in bowl until combined. Add sugar and whisk until smooth. Spread glaze evenly over bars. Scatter sprinkles, if using, over top. Let glaze set fully, about 1 hour.
5. Using foil overhang, lift bars out of pan and transfer to cutting board. Cut into 24 pieces and serve. (Bars can be stored in airtight container at room temperature for up to 3 days.)
