Rhubarb Brown Butter Bars

  in Desserts, Recipes

Have you ever made a rhubarb dessert without strawberries? If not, now’s your chance! This recipe lets the perennial vegetable shine on its own. Hibiscus flowers are optional, but they lend a subtle floral flavor and deep pink color to the jam. You can find dried hibiscus flowers at Oryana near the bulk tea section.

Recipe adapted from Bon Appetit

JAM (yields 1½ – 2 cups)
Zest of 1 grapefruit (about 1 tablespoon)
Juice of ½ grapefruit
1 tablespoon dried hibiscus flowers (optional, but recommended)
¾ cup granulated sugar
¼ teaspoon kosher salt
¼ teaspoon vanilla bean paste (or ½ teaspoon vanilla extract)
1 lb rhubarb, sliced into ½ inch thick pieces (about 4 cups), divided

BARS
1¼ cups hazelnuts
¾ cup (1½ sticks) unsalted butter, cut into pieces
1¼ cups all-purpose flour
1¼ cups old-fashioned oats
¼ cup plus 1 tablespoon dark brown sugar, packed
¼ cup granulated sugar
1 teaspoon salt
½ teaspoon baking soda

To make the jam:

  1. Combine grapefruit zest, grapefruit juice, hibiscus flowers, sugar, and salt in a medium saucepan. Bring to a boil over medium heat and allow sugar to dissolve (about 1 minute).
  2. Set aside ½ cup rhubarb and add remaining rhubarb (about 3 ½ cups) to the pan. Reduce heat to a simmer. Stir frequently and mash rhubarb with a wooden spoon. Cook until rhubarb is soft and mixture is thickened, about 10-12 minutes.
  3. Remove pan from heat and stir remaining 1/2 cup rhubarb into jam. Add vanilla. Allow mixture to cool at room temperature. Once cool, remove hibiscus leaves and discard.

To make the bars:

  1. Preheat oven to 350°F. Grease an 8×8 (or 7×11) pan and line with parchment paper.
  2. Toast hazelnuts on a rimmed baking sheet until fragrant and slightly darker in color, about 7 minutes. Let cool, then rub skins off and discard them. Chop hazelnuts coarsely.
  3. Cook butter in a small saucepan over medium heat, stirring often until butter foams and begins to brown (about 5-10 minutes). Once butter takes on a nutty aroma and light brown color, transfer it to a heatproof bowl. Include all of the browned bits from the bottom of the pan.
  4. In a large bowl, whisk the flour, oats, brown sugar, granulated sugar, salt, and baking soda. Next, whisk in chopped nuts. Pour in the browned butter and mix to combine. Transfer about 2/3 of the mixture to the prepared pan and use your hands to press the mixture into an even layer.
  5. Spread jam over the prepared layer, leaving a ¼” border around the edges. Crumble remaining nut mixture over top. Note: We used about 1½ cups of jam and had about ½ cup remaining.
  6. Bake for 40-45 minutes at 350°F, rotating pan halfway through. Let bars cool completely before cutting.