For the cake, grease and flour a 13x9 baking dish and set aside. In a mixing bowl, beat flour, sugar, baking powder, baking soda and salt on low until combined. Beat in softened butter until mixture is crumbly. Add in eggs, vanilla and buttermilk and beat until fully combined and fluffy! Pour half the batter into baking dish, spreading evenly.
In a separate mixing bowl, beat cream cheese with sugar and egg until light and fluffy, about 3-5 minutes. Pour over batter. Top with remaining half of cake batter.
For the topping, mix sugars with cinnamon and salt. Add in butter and combine fully. Add flour and mix with hands until fully combined. Pour crumb topping over batter, sprinkling with hands until evenly distributed.
Bake cake in a 325 degree oven for about 45 minutes, until fully cooked. Cool completely and serve.