Chocolate Coffee Cake

I made this cake for a gathering at the cafe in our mosque. Someone who was also coming to the gathering liked coffee flavored sweets (I think), so I decided to make a coffee flavored cake in hopes that they'd enjoy it.

Ingredients for chocolate cake:
1 1/3 cup all purpose flour (220g)
1 1/4 cup granulated sugar (250g)
1/2 cup cocoa powder (50g) (not Dutch-process)
1/2 tsp baking powder
1/2 tsp baking soda
1/4 tsp sea salt
2 eggs
2/3 vegetable oil (115g)
1 cup milk (225g)

For Soak
150g sugar
150g water
2 tsp Instant coffee

For filling (Coffee Italian meringue buttercream)
6 egg whites
1 1/4 cup granulated sugar (220g)
4 tbsp water (50g)
4 sticks butter (450g)
1 tsp vanilla
Pinch of salt
4 tbsp water (50g)
1 tbsp Instant coffee

the first water measurement is for the sugar syrup that you'll heat up. the second measurement of water is for mixing in the instant coffee.

Tips:

If your filling curdles and is not emulsifying. Try heating the bowl of the stand mixer very gently with a blow torch while it mixes.
You can make the italian meringue buttercream without a stand mixer too, although it will be harder. You'll have to use a regular mixing bowl and a mixer instead.
I recommend sifting all the dry ingredients to prevent lumps from developing in the batter! especially because we're adding cocoa powder and it usually has quite a few lumps.
For the ganache, I keep it in a plastic container until I need to use it. Then, I heat it in the microwave in increments of 20 seconds until it is just warm and fluid. I use it right away then.
If you want to prevent a dome from developing on your cake, try covering the sides of the cake pan with foil for when it bakes, or bake at a lower temperature and for a longer period of time.