Cook rhubarb over low heat until juice begins to run; then add sugar replacement and fructose.
Dissolve cornstarch in a small amount of cold water and add to rhubarb mixture.
Cook and stir until mixture begins to thicken.
Remove from stove.
Cool while making cake batter.
Combine cake mixes in a large mixing bowl (Remember you have to double the amount of ingredients on the package because you have two cake mixes.) Beat the almond extract into the batter.
Pour rhubarb mixture into a greased 8 in.(20 cm) sq. cake pan.
Pour batter over rhubarb.
Bake at 375°F (190°C) for 35 to 45 minutes or until tester inserted in middle comes out clean.
Turn out onto a cake plate.