Clean the rhubarb and chop it into 1/2-inch pieces. Put in a bowl, sprinkle with 2 tablespoons sugar, and let sit several hours or overnight, till the rhubarb releases some of its juice.
Place the rhubarb and its juice in a heavy saucepan, add the 1/2 cup sugar and undrained pineapple, and stir to combine. Cook over medium heat, stirring occasionally, until the mixture is like thick applesauce. Stir more frequently toward the end of the c
Heat the milk and butter, cut in pieces, in a saucepan over medium heat until the mixture reaches about 120°F. Combine 1 cup of flour, sugar, yeast and salt in a bowl. Pour the milk mixture over the dry ingredients, stirring to mix well. Beat in the eggs
Beat the cream cheese, eggs, sugar and vanilla until smooth. Set aside.
Mix the flour, sugar and cinnamon in a medium-sized mixing bowl. Cut in the butter, as you would for pie crust, working it in until mixture is coarse and crumbly.
Butter a 12 x 18 x 1-inch rimmed baking sheet (a half-sheet pan). Punch the dough down, and divide it into two pieces. On a large, well-floured surface, roll one piece of dough into a 12 x 18-inch rectangle. Fit into the pan. Spread the cheese filling on
Bake the cake for 45 minutes, or until cake is golden brown and firm to the touch. Serve warm or at room temperature.