Split the vanilla bean lengthwise and scrape the seeds into a tiny bowl. Add the vanilla extract and mix to combine.
In a large heatproof bowl, mix together egg yolks, erythritol, and vanilla. In a medium-size saucepan, bring some water to boil and reduce the heat until the water is simmering. Suspend the bowl with yolks over the water, making sure the bowl is not touching the water. Using an electric mixer, beat continuously for 4-5 minutes until the mixture is pale and creamy. Let the mixture cool down in the fridge before you continue. Mix in the vodka (optional).
Using a stand electric mixer, whisk the chilled whipping cream until stiff peaks are formed (about 2 to 3 minutes on high). Do not over whip.
Gently fold about ⅓ of the cooled egg yolk mixture into the whipped cream. Transfer the rest of the yolk cream into the bowl and gently fold in until the mixture smooths out and becomes soft and silky. Try not to deflate the mixture by over mixing. You want it to remain airy.
Transfer half of the vanilla ice cream to a pan than can be sealed. Pour half of the raspberry sauce onto the first layer, and make swirls with a knife or a spoon. Add the rest of the ice cream on top and pour the rest of the raspberry sauce on it. Make the swirls.
Gently cover the ice cream with a small piece of plastic wrap or parchment paper (or both). Seal the top and freeze for at least 6 hours. Enjoy within two weeks (if you can keep it for that long)!