Preheat oven to 180°C. Line an oven tray (about 20x30cm) with baking paper.
Arrange crackers onto tray, covering the entire tray.
Place butter, brown sugar and a pinch of salt in a small pot on medium-high heat. Once melted, reduce heat to medium and cook, stirring for about 3 minutes, until caramel mixture has thickened slightly.
Pour caramel mixture over crackers and bake in oven for about 12 minutes, until caramel is bubbling and starting to brown.
While caramel bakes, melt chocolate in a small pot on low heat. Alternatively melt in the microwave in 30 second bursts, stirring in between.
Once caramel has cooked, remove from oven and top with melted chocolate, peanuts and a sprinkling of flaky sea salt.
Allow to cool, then place in the fridge to harden for at least 30 minutes. Break bark into pieces and store in an airtight container in the fridge.
Tip: Make sure your baking tray is completely covered with paper to prevents any caramel from sticking to it!