Preheat oven to 350 degrees. Line a 9x9 pan with parchment paper.

In a large bowl combine flour, baking powder, baking soda, salt and sugar. Stir well.

In a second bowl, crack and lightly beat the eggs. Then add in the oil, cashew butter, milk and vanilla. Whisk until well combined.

Pour the wet ingredients into the dry and fold together until well incorporated, about 20 strokes.

Pour batter into prepared pan. Bake in preheated oven for 25-30 minutes, until center springs back when gently poked. Do not over bake or the cake will be dry.

Remove cake from oven and cool in pan for 10 minutes, then turn out onto a wire rack to cool completely.

Place the chopped chocolate into a heat proof bowl.

Place the milk, liqueur and sugar into a small saucepan. Heat over medium temperature until the sugar melts and the milk begins to simmer. Stir frequently.

Pour the hot milk over the chocolate. Let sit for 2 minutes, then stir until all the chocolate is melted. Once the chocolate is smooth, pour it onto a baking sheet and spread it into an even layer. Chill in the refrigerator for 20 minutes.

Cut the room temperature butter into cubes and place into an electric mixer. Beat on medium high speed until smooth. This will take about 4-5 minutes. Stop a couple of times to scrape down the bowl. Once the butter is smooth, scrape the cooled chocolate from the baking sheet and put it into the mixer. Beat on high speed until a light fluffy frosting is formed.

Spread the frosting on the cooled cake.

Top with chopped nuts, if you like.

Store the cake in an airtight container in the refrigerator for up to 2 days.