Preheat the oven to 180C/350F/Gas 4. Line an 8x8-inch square baking pan with foil or parchment paper, and set aside.
Place the butter, sugar, cocoa powder, and salt into a microwave-safe bowl, and microwave in 30 second intervals, stirring after each one, until the butter is melted and the mixture feels very warm to the touch.
Mix in the eggs, one at a time. Stir in the mint extract. Fold in the flour until fully combined, then fold in the chocolate chips. Gently fold in the strawberries.
Pour the batter into the prepared pan, and spread out evenly. Top with a few extra strawberry halves if desired, then bake for 35 - 40 minutes, or until a toothpick inserted into the centre comes out almost clean with a few moist crumbs. Allow to cool completely in the pan on a wire rack before cutting into squares.
Notes
Brownies stay fresh, stored in an airtight container, in the fridge for up to 1 week. They also freeze well for up to 3 months. Thaw overnight in the fridge before serving.