Add 1 stick butter to a small saucepan set over medium heat, cooking until the butter begins to brown, about 3-4 minutes. Remove from the heat and transfer to a heatproof bowl. Stick in the freezer to chill, 10-15 minutes, but no longer.Preheat the oven to 350° F. Line a 9x13 inch baking dish with parchment paper. In a large mixing bowl, beat together the remaining stick of butter, the cooled browned butter, brown sugar, and vanilla until creamy. Add the flour and mix until fully combined. Press the dough into the prepared baking dish. Bake 20-22 minutes, until lightly golden and toasted. Remove from the oven and let cool.To make the caramel. In a medium pot, combine the sweetened condensed milk, butter, and maple. Bring to a boil over medium heat, whisking consistently. Cook the mixture until it turns golden brown in color and has thickened, about 15-20 minutes. Make sure to stir often to avoid burning the milk. Little brown bits are OK. Remove from the heat and whisk in the vanilla. Immediately pour the caramel over the shortbread and spread in an even layer. Transfer to the fridge to chill, at least 1 hour or 30 minutes in the freezer. Melt the chocolate and coconut oil together in the microwave until melted and smooth. Cut the bars into 24 rectangle bars or 48 square bars. Freeze another 10 minutes to make dipping easier, then cover/dip each bar in chocolate. Return to the freezer to let the chocolate set up, about 10 minutes. Keep stored in a cool dry place or in the fridge for up to 2 weeks.