It's important to have your cream cheese at room temperature otherwise the filling will become grainy. You will need one 9" springform pan. Gel food coloring produces more intense colors. To make purple food coloring with liquid coloring: Place ten drops of red food coloring into a small bowl. Add five drops of blue coloring to the red. Whisk the red and blue together to create purple. Drop in additional red food coloring, one drop at a time, to lighten the purple or more blue coloring to darken it.