Preheat oven to 350ºF and spray a 9x13-inch baking dish with nonstick cooking spray. Prepare white cake mix according to box instructions.

Divide cake batter evenly among four bowl, then dye each to desired shade. Pour each batter into each corner of the baking dish (see photo above). Bake for 32-35 minutes, or until toothpick inserted in the center comes out with few moist crumbs attached. Cool completely.

In the bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream until stiff peaks form. Transfer whipped cream to another bowl, then return mixing bowl to mixer. Switch out whisk attachment with the paddle attachment.

To the mixer, add the cream cheese, Funfetti cake mix, lemon juice, extracts, and salt. Beat on high until smooth. Add powdered sugar, and continue beating. Mixture will be thick. Gradually stir in the milk until smooth and creamy. Fold in the sprinkles.

Transfer filling to a pastry bag or a gallon-sized ziploc bag with the tip of the corner cut off.

Take one pink starburst and one yellow starburst. Soften each individually by heating in the microwave for 5 seconds. Unwrap both starbursts, then roll each into a long skinny log, making sure that the ends are pointed and each log is of equal length.

Place the yellow and pink skinny log side by side, press the tips together, then slowly twist them around each other until you reach the bottom. Press the bottom two tips together. Cut twisted log in half to make two unicorn horns. Repeat with remaining starbursts.

Take a marshmallow and use clean scissors to cut marshmallow slightly less than on the diagonal (see photo above). Do the same with the other side of the marshmallow that you just cut the first ear off of. Pinch the tips of the ears together. Dip the sticky side of the marshmallow into sprinkles. Repeat with remaining marshmallows.

Cut cooled cake into little cubes. Coarsely chop all but 6 Oreo cookies (you can just eat these). Place about half of the cake cubes into the bottom of each jar, then pipe about half of the filling on top. Divide the chopped Oreo cookies evenly among the jars, shaking slightly to create an even layer. Add another layer of cake cubes, followed by the rest of the filling. Top each trifle with two "unicorn ears", one "unicorn horn", and more sprinkles, if desired.