Preheat oven to 350 degrees. In the bowl of a stand mixer (or with hand mixer), mix together flour, brown sugar, pecans, and butter on medium speed until butter is pea-sized and mixture looks like coarse crumbs.
Pour half of the mixture into a parchment-lined 9×13″ pan. Press into pan and bake for 10-15 minutes or until lightly browned around edges.
In medium-sized bowl, mix together rhubarb, strawberries, corn starch, and 1/2 cup sugar. Set aside.
In the bowl of a stand mixer, mix together cream cheese and remaining 1 1/2 cups sugar until light and fluffy. Add eggs and vanilla on medium until smooth.
Pour cream cheese mixture on top of crust and spread evenly. Evenly pour strawberry mixture on top of cream cheese. Top with remaining crumb topping.
Bake for 40-45 minutes or until edges are browned and middle is slightly wobbly when shaken. Cool on cooling rack for 1 hour then refrigerate for 3 hours or overnight. Refrigerate leftovers.