Start by preheating your oven to 350°F. Grease a 9x13-inch baking pan and line the bottom with parchment paper. I usually leave a little parchment hanging over the sides because it makes lifting the cake out much easier later.

The first time I made this Mary Berry Coffee Fudge Traybake Recipe, I skipped the parchment paper because I thought buttering the pan was enough. Bad idea. A few pieces stuck in the corners and looked messy. It still tasted good, thankfully.

In a small bowl, stir the instant coffee granules with hot water until dissolved. Let it cool for a minute or two.

You want the coffee mixture smooth and dark without any dry granules left behind. If the coffee is too hot when added later, it can slightly affect the butter mixture.

In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar together until the mixture looks pale and fluffy. This usually takes about 3 to 4 minutes with a hand mixer.

Do not rush this step. The air you beat into the butter helps give the cake a lighter texture. I noticed when I only mixed for a minute, the traybake came out denser.

The mixture should look creamy and almost whipped when it’s ready.

Add the eggs one at a time, mixing after each addition. If the batter looks slightly curdled, don’t panic. Mine does that half the time.

What worked better for me was adding one spoonful of flour between eggs if the mixture started looking separated. That helps stabilize everything.

In another bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients into the butter mixture, alternating with the milk. Stir gently after each addition.

Pour in the dissolved coffee mixture and vanilla extract. Mix until everything is fully combined, but stop once the batter looks smooth. Overmixing can make the cake slightly tough.

The batter should look thick but spreadable.

Spread the batter evenly into the prepared pan. Use a spatula to smooth the top.

Bake for about 26 to 30 minutes. Every oven runs a little differently, so start checking around the 25-minute mark.

The cake should look lightly golden around the edges and spring back gently when touched. A toothpick inserted in the center should come out with a few moist crumbs but not wet batter.

The smell at this point is honestly one of the best parts. The kitchen starts smelling like coffee, brown sugar, and warm butter.

Let the cake cool completely before adding the topping.

In a medium saucepan, melt the butter over low heat. Stir in the milk and instant coffee granules until dissolved.

Add the chopped chocolate and stir until melted and smooth.

Remove the pan from the heat and gradually whisk in the powdered sugar and pinch of salt. The mixture should become glossy and thick but still pourable.

If the frosting looks too thick, add a tiny splash of milk. If it seems too thin, let it sit for a couple minutes before spreading.

The first time I made the topping, I added all the powdered sugar too quickly and ended up with lumps. Slow and steady actually matters here.

Pour the warm fudge topping over the cooled traybake and spread it evenly with a spatula or butter knife.

You can leave the top plain or add chocolate shavings, chopped nuts, or cocoa powder.

Let the topping set for about 30 minutes before slicing. It firms up into this soft fudge-like layer that cuts nicely without becoming hard.

Cut the traybake into squares or rectangles.

I usually wipe the knife between cuts because the fudge topping can get a little sticky. If you want cleaner slices, chill the traybake for about 20 minutes before cutting.

This Mary Berry Coffee Fudge Traybake Recipe tastes really good slightly chilled, but I personally like it best at room temperature with hot coffee.