Shortbread with salted caramel

Ingredients:

• 330 g unsalted butter, plus extra for greasing the pan
• 1 cup granulated sugar
• 2 tsp vanilla extract
• 2.5 cups premium flour
• 0.5 cup light brown sugar
• 3 tablespoons light corn syrup
• 2 tbsp. heavy cream
• 1 tsp instant espresso powder
• 1/4 teaspoon coarse salt
• 0.5 tsp apple cider vinegar
• Sea salt flakes, for sprinkling

Preparation:

1. Preheat oven to 350°F (175°C). Grease a 22x32cm baking pan with butter, then line with parchment paper, leaving an overhang on both sides; grease the parchment with butter.
2. In a large bowl, beat 275g of butter, granulated sugar, and 1 teaspoon of vanilla extract with a mixer on medium speed until light and fluffy, 3-5 minutes. Reduce mixer speed to low, add flour, and beat until fully incorporated.
3. Transfer the dough to the prepared baking pan and place a piece of plastic wrap directly on the surface. Press into an even layer, then remove the wrap. Bake until golden brown, 30-35 minutes. Transfer the cake to a wire rack to cool slightly, then remove from the pan by pulling the parchment overhangs. Cut into triangles.
4. Prepare the caramel:
   
   Combine the remaining 2 ounces (55 grams) of butter, brown sugar, corn syrup, heavy cream, espresso powder, and coarse salt in a small saucepan and heat over medium heat. Cook, stirring occasionally, until the mixture reaches 230°F (113°C) on a candy thermometer, about 6 minutes.
5. Remove from heat and stir in the remaining 1 teaspoon vanilla extract and vinegar. Let cool for 5 minutes, then drizzle the caramel over the shortbread. Sprinkle with sea salt.