Pot of Gold Surprise Cake

Ingredients:

Cake

• 2.5 cups of premium flour, plus extra for dusting the pans
• 1 tbsp baking powder
• 3/4 tsp salt
• 165 g butter, room temperature
• 1 and 1/3 cups sugar
• 4 large egg yolks, room temperature (use the whites for the glaze)
• 1 tbsp vanilla extract
• 1 and 1/3 cups whole milk

Glaze and filling

• 4 large egg whites, room temperature
• 2/3 cup sugar
• 1/3 cup amber syrup or honey
• 1 teaspoon vanilla extract
• 220 g plus 6 tbsp (90 g) butter, cut into pieces and slightly softened
• 1.5 cups gold M&M's
• 1 small package of edible gold powder (available at specialty stores or online)

Preparation:

1. Preheat oven to 350°F (175°C). Coat two 8-inch round cake pans with cooking spray and line the bottoms with parchment paper. Spray the parchment paper with cooking spray and dust the bottom and sides of the pans with flour, shaking off any excess.
2. Preparing the biscuit: In a medium bowl, whisk together flour, baking powder and salt.
   
   In a large bowl, beat the butter and sugar with a mixer on medium speed until light and fluffy, 3 to 5 minutes. Reduce the mixer speed to low; add the egg yolks one at a time, adding the next yolk only when the previous one is completely incorporated. Add the vanilla. Beat in 3 additions of flour, alternating with 2 additions of milk, until completely combined (it's okay if the batter resembles cottage cheese). Reduce the mixer speed to medium and beat for another 1 minute.
3. Divide the batter between the prepared pans and spread it evenly. Bake for about 40 minutes, rotating the cakes halfway through; the tops should be golden brown and the centers should spring back slightly when pressed lightly. Let them rest in the pans for 15 minutes, then run a knife around the edges of the cakes to loosen them from the sides. Transfer to a rack and let cool completely; discard the parchment.
4. Preparing the glaze: In a medium saucepan over medium heat, heat a few centimeters of water to a gentle simmer.
   
   In the bowl of a stand mixer, beat the egg whites with the sugar and syrup. Place the bowl over a saucepan and melt, stirring, until the sugar dissolves, the egg whites are foamy, and the mixture is warm, about 5 minutes. Transfer the bowl to a stand mixer and beat with the whisk attachment on medium-high speed until stiff, glossy peaks form.
5. Switch the whisk to the paddle attachment. Stir in the vanilla, then continue mixing until smooth, gradually adding the butter a few pieces at a time (it's okay if the icing looks uneven).
6. Using a paring knife, cut a 9cm diameter hole in the centre of the cake; set both pieces aside for now.
7. Mark a 9-cm circle in the center of another cake layer and scoop out the center with a spoon, leaving the center halfway down. Carefully transfer the cake layer to a serving platter. Spread 1 cup of glaze over it (avoiding the center).
8. Place the first cake layer with a hole through it on top of the second cake layer and fill the resulting well with M&M's.
9. Trim the top 1/2 inch horizontally from the remaining 9 cm cake layer and place it on top of the candies to form a lid.
10. Cover the entire cake with the remaining icing. Refrigerate for about 20 minutes to allow the icing to set slightly.
11. Dip a small dry brush into edible gold and decorate the cake with gold, tapping the brush and working it into hard-to-reach areas.