Preheat your oven to 350°F (175°C). In a mixing bowl, combine the all-purpose flour, melted unsalted butter, powdered sugar, vanilla extract, and salt. Mix until a crumbly texture forms. Press this mixture firmly into the bottom of a lined 9x13-inch baking pan. Bake for 17-20 minutes, or until the edges are lightly golden brown, then allow it to cool completely.

In a medium saucepan, whisk together the 2% milk, coconut milk, granulated sugar, corn starch, salt, and egg yolks until fully combined. Cook over medium heat, constantly whisking, until the mixture comes to a gentle boil and thickens, about 5-7 minutes. Once thick, remove from heat and stir in the butter, shredded coconut, and a splash of vanilla extract until smooth.

Pour the warm coconut pudding filling over the cooled shortbread crust, using a spatula to spread it evenly. Cover the pan with plastic wrap and place it in the refrigerator. Chill for at least 4 hours, or until the filling is set and firm.

In a mixing bowl, beat the heavy whipping cream, sugar, and vanilla extract on high speed until medium-stiff peaks form, about 2-4 minutes.

Once the coconut filling is set, remove it from the refrigerator. Gently spread the whipped cream over the top of the pudding layer. Optionally, sprinkle with toasted coconut flakes. Slice into bars and serve chilled.