In a microwave safe bowl, add in the butter. Place in the microwave for two 30 second intervals.
In a large mixing bowl, add in the sugars and cocoa powder. Whisk together to remove the lumps.
Add the butter, hot water, and vanilla into the dry ingredients. Whisk until everything is combined.
Add in the lightly beaten eggs and continue whisking until smooth.
Add in the baking soda and flour and whisk until incorporated. There may be a few lumps in the batter.
Stir the chocolate chips into the batter.
Preheat oven to 350 degrees. Line the bottom of a 9x13 with parchment paper. Spray non-stick cooking spray on the sides of the pan and parchment paper.
Place in the oven for 30-35 minutes or until done. Let cool.
Filling
In a medium size saucepan, add in the sugar and egg yolks. Whisk together until combined.
Add in the sweetened condensed milk and butter. Place the saucepan over medium/low heat. After the butter melts, turn the heat up to medium and whisk occasionally. Let the mixture cook until it thickens. I cooked mine approximately 10 minutes.
Pour the mixture into a bowl. Add in the vanilla, 1 cup of coconut, and pecans. Stir with a spatula until combined.
Buttercream
Place the chocolate chips in a microwave-safe bowl. Microwave in 30 second intervals and stir afterwards. Mine took three 30 second intervals to completely melt the chips into a smooth mixture.
Add the butter and chocolate chips into a mixing bowl. Mix until combined.
Add in the corn syrup and powdered sugar and mix on low until the powdered sugar is combined. Turn the mixer on high and let it whip for another 3 minutes until light and fluffy. If the mixture is too thick for you, add a tablespoon of milk to thin out.
Assemble
Using a glass that has a opening about the same size as the cups you're using for your trifle, cut out 6 circles from the brownies.
Place the brownies on the bottom of the cup. Add a decent scoop of filling on top of the brownie and push to the edges of the cup.
Place the frosting in a piping bag and pipe out a layer of frosting. Repeat the layers. Top with the trifles with the remaining ¼ cup of toasted coconut for garnish.