Preheat oven to 180°C (350°F) and grease a baking pan.
Cream softened butter and granulated sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition.
Stir in dissolved coffee and vanilla extract.
Alternately add flour and milk, mixing gently to form smooth batter.
Pour half the batter into prepared pan.
Bake cake first, then slice and add whipped cream layer before serving.
Add remaining batter evenly on top.
Mix streusel ingredients until crumbly and sprinkle over cake.
Bake 40–50 minutes or until a toothpick inserted in cake portion comes out clean.
Cool slightly before slicing and serving.