Add 3/4 cup heavy cream to a medium-large mixing bowl. Combine honey, rum, and vanilla in a small measuring cup. Set aside. With a hand mixer set to high, beat heavy cream for 1-2 minutes, or until it begins to thicken. Once cream begins to thicken, with mixer still running, slowly incorporate honey, rum, and vanilla, and continue to beat, 1-2 minutes, until soft peaks form. Serve immediately, or make up to 5 hours in advance and refrigerate in an airtight container until ready to serve (may keep overnight, but made same day is ideal).