Preheat oven to 350°. Cream butter and sugar until light and fluffy. Beat in egg and vanilla. In another bowl, whisk flour, baking powder, cinnamon and salt; add to creamed mixture alternately with milk, beating well after each addition. Spread three-fourths of batter into a greased 9-in. springform pan (batter will be thick). Set remaining batter aside.
In another bowl, beat cream cheese, sugar and flour until smooth. Beat in vanilla. Add eggs; beat on low speed just until combined. Pour over batter.
Mix cinnamon filling ingredients. Drop by tablespoonfuls over cream cheese mixture. Cut through cream cheese filling with a knife to swirl the cinnamon filling. Drop reserved batter by tablespoonfuls over filling. Place pan on a baking sheet.
Bake until center is almost set, 70-80 minutes. Cover top loosely with foil during the last 30 minutes if needed to prevent overbrowning. Cool on a wire rack 10 minutes. Carefully run a knife around edge of pan to loosen. Cool 1 hour; remove sides of pan. Serve warm. Refrigerate leftovers.