Preheat the oven to 350°F. Grease and line an 10x8-inch baking pan with parchment paper, leaving a little overhang for easy removal.
In a large bowl, whisk together flour, brown sugar, white sugar, cocoa powder, baking powder, and salt.
In a separate bowl, whisk together the plant-based milk, melted vegan butter, applesauce, and vanilla extract until well combined.
Add the wet ingredients to the dry ingredients and stir until combined. Don't over mix. Fold in the vegan chocolate chips.
Pour the brownie batter into the prepared pan and spread it evenly.
Bake in the preheated oven for about 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Allow it to cool completely.
To make the raspberry truffle layer, add the chopped vegan dark chocolate, full-fat coconut milk, coconut oil, and pinch of salt to a small saucepan. Warm over low heat, stirring often, until the chocolate is melted and the mixture is smooth.
Remove from the heat and stir in the raspberry jam and lemon, if using, until fully combined.
Spread the raspberry truffle mixture evenly over the cooled brownies.
Refrigerate for at least 2–3 hours, or until the truffle layer is firm and set.
Once set, lift the brownies from the pan using the parchment paper. Cut into squares and serve.