Using either a stand mixer, handheld mixer or regular whisk and a large bowl, whisk the heavy cream with ½ cup powdered sugar until it thickens and stiff peaks form. Make sure the cream is chilled thoroughly before beating. Be careful not to over mix, otherwise you will turn the cream into butter! Transfer the whipped cream into a separate bowl for later.
Sprinkle the gelatin/agar agar powder over the room temperature water and let sit for 10-15 mins. Then, transfer it into a saucepan on the stove-top along with the guava paste and heat it on medium heat, until it has completely melted and you have a thick homogenous mixture. If using agar agar, make sure this mixture comes to a boil before you take it off the heat.
In a separate bowl, beat the cream cheese for 2-3 minutes until it turns smooth and creamy. Add ¼th cup of powdered sugar and beat until everything is well combined.
With the mixer still running, pour in the hot guava mixture into the cream cheese and continue mixing until it is nicely combined.
(This step is optional for added color)Puree the beet with ¼ cup water (or use beet powder) and add it into the bowl. Mix again until you have a homogenous mixture.
Fold in the reserved whipped cream mixture into the guava filling in 3-4 additions, mixing gently and making sure to keep as much air as possible.
Pour the cheesecake filling evenly over the biscuit base. Tap on the counter top a few times to level the surface and release any air bubbles. Now, refrigerate the cheesecake for 3-4 hours.