Rhubarb–Brown Butter Bars
Spring is in the air! This time of year I always think of rhubarb and my grandma. I loved learning to bake with her. Rhubarb is easy enough to spot because of their huge, ruffled leaves. The leaves are not edible, but digging inside you find the thick leaf stalks that range in color from glossy red to light green with ruby bases. The stalks are what you’ll use in this rhubarb recipe! Here is a nice sweet treat for the month of April that will have you enjoying the bounty of the Spring season. Not sure where to get rhubarb? Check in with Goodside Grocery: Sheboygan’s only organic food co-op!
Ingredients
JAM
Zest and juice of ½ grapefruit or 1 orange
3 dried hibiscus flowers (optional)
¾ cup (150 g) granulated sugar
¼ tsp. kosher salt
1 vanilla bean, split lengthwise (optional)
1lb. rhubarb, sliced crosswise into ½”-thick pieces (about 4 cups), divided
ASSEMBLY
Nonstick cooking oil spray
1¼ cups blanched hazelnuts, raw pecans, and/or raw or blanched almonds
¾ cup (1½ sticks) unsalted butter, cut into pieces
1¼ cups (156 g) all-purpose flour
1¼ cups (125 g) old-fashioned oats
¼ cup plus 1 Tbsp. (packed; 63 g) dark brown sugar
¼ cup (50 g) granulated sugar
1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt
½ tsp. baking soda
PREPARATION
JAM
Combine grapefruit zest and juice, hibiscus flowers (if using), sugar, and salt in a medium saucepan; scrape in seeds from vanilla bean and add pod. Bring to a boil over medium heat. Reduce heat and simmer, stirring occasionally, until sugar is dissolved, about 45 seconds.
Set aside ½ cup rhubarb; add remaining rhubarb to pan and simmer, stirring often and mashing with a wooden spoon, until rhubarb is softened and mixture is thick and jammy, 10–12 minutes.
Remove pan from heat and stir reserved rhubarb into jam. Let cool. Remove vanilla bean and hibiscus; discard. (You should have about 1½ cups jam.)
Do ahead: Jam can be made 5 days ahead. Transfer to an airtight container; cover and chill.
ASSEMBLY
Preheat oven to 350°. Coat an 8x8” pan with nonstick spray, then line with parchment paper, leaving an overhang on 2 sides. Coat parchment. (These bars have a tendency to stick.)
Toast nuts on a rimmed baking sheet until fragrant and slightly darkened, 5–8 minutes. Let cool, then chop very coarsely (it’s okay to cut some just in half).
Meanwhile, cook butter in a small saucepan over medium-low heat, stirring often, until it foams, then browns, about 5 minutes. Immediately pour into a small heatproof bowl, making sure to include all of the brown bits.
Whisk flour, oats, brown sugar, granulated sugar, salt, and baking soda in a large bowl to combine, then whisk in nuts. Drizzle in butter and, using a rubber spatula, mash into dry ingredients until a clumpy, wet mixture forms (it should hold together when squeezed in your hand). Transfer 3 cups mixture (no need to pack) to prepared pan. Using your hands, press and compact into an even layer.
Spread jam over base, leaving a ¼” border to prevent jam at the perimeter from getting too dark, then crumble remaining nut mixture over. If you’d like bigger clumps, press the mixture together in your hands before scattering over jam.
Bake, rotating pan halfway through, until top feels firm and is deep golden brown, 40–45 minutes. Let cool in pan, then use parchment overhang to remove. Transfer to a cutting board and slice into 16 bars. (Chilling for a couple hours first will make them even easier to slice.)
Do ahead: Bars can be baked 5 days ahead. Transfer to an airtight container; cover and chill.