2 pints fresh blueberries, stemmed and rinsed
½ cup Lyle's Golden Syrup (available at larger grocery stores, on the baking aisle)
Finely grated zest and juice of 1 lemon
1 ounce mascarpone cheese
¼ cup granulated sugar
2 cups chilled heavy cream
8 ounces graham crackers, or more as needed
Confectioners' sugar, for serving
Purée the blueberries in a food processor until smooth. Use a flexible spatula to push the purée through a fine-mesh strainer, pressing to extract as much as possible from the solids (discard them). There should be about 2 cups of strained purée. Return it to the food processor, along with the syrup and 2 tablespoons of the lemon juice, and blend until well incorporated. Reserve 1 cup as a sauce for serving; cover and refrigerate it.
Add the mascarpone to the remaining blueberry mixture (in the food processor) and blend until the mixture becomes uniform and smooth.
Combine the lemon zest, granulated sugar and heavy cream in the bowl of a stand mixer or hand-held electric mixer. Beat on low speed for about 1 minute, then on medium-high speed for about 2 minutes or until stiff peaks form.
Use parchment paper to line the bottom and sides of the loaf pan (an initial light coating of cooking oil spray may help). Use an offset spatula to spread half of the blueberry-mascarpone mixture evenly in the bottom. Cover completely with the graham crackers, making a single layer that uses about one-quarter of the crackers; breaking them as needed.
Next, use the spatula to spread half of the lemon whipped cream evenly over the graham cracker layer, then repeat with another graham cracker layer, the remaining blueberry mascarpone mixture, a graham cracker layer, the remaining lemon whipped cream and a final graham cracker layer. Compress very gently; the assembled cake should come to the top of the pan. Wrap in plastic wrap and weight with a heavy plate or pan. Refrigerate for at least 4 hours and up to a day in advance.
To serve: Remove the weight and plastic wrap. Place a platter over the pan, then use both hands to invert the cake so it lands on the platter. Gently peel away the parchment paper and discard it.
Whisk the reserved cup of blueberry purée so it becomes smooth and pourable. Drizzle some over each slice of cake, then sprinkle with confectioners' sugar. Serve right away.
Serves eight to 10.
Nutrition values per serving (based on 10): 520 calories, 35 g fat (21 g saturated fat), 52 g carbohydrates, 3 g fiber, 28 g sugar, 3 g protein, 105 mg cholesterol, 230 mg sodium.
Food writer and cookbook author Tony Rosenfeld for The Washington Post