Preheat the oven to 350 °F (177 °C). Prepare a 8-inch square pan with parchment paper or cooking spray. Set aside.
In a small bowl mix together all streusel topping ingredients. Place in the fridge while you prepare the rest of the cake.
In a large bowl mix together with hand mixer softened butter, granulated sugar, and brown sugar until combined. Add in egg and vanilla extract, mix again. Add in milk and apple cider, beating one final time. Set aside.
In a separate medium bowl combine flour, salt, and baking soda. Add half the dry ingredients into your wet ingredients and combine with a rubber spatula. Add in remaining dry ingredients and cubed apples and mix again. Do this until just combined. This makes sure not to over mix. Pour batter into a greased pan and spread evenly with a spatula. Batter will be thick. Top with streusel topping and bake for 60-65 minutes.
While the cake is baking, make the glaze. In a small bowl combine glaze ingredients. Allow the cake to cool for one hour before drizzling glaze. Drizzle using a piping bag or spoon. Enjoy!