Preheat oven to 180C. Grease six 1-cup (250ml) glass jars.
Beat butter, Natvia, eggs, sifted flour, milk, vanilla seeds and extract in a a small bowl with an electric mixer on low speed until ingredients are combined. Increase speed to medium; beat until mixture has change to a paler colour. Spoon 1/2 up of mixture into each jar.
Place jars in a large baking dish. Pour boiling water into dish until water comes halfway up the sides of the jars.
Bake cakes for 40 minutes or until golden and cakes spring back when pressed lightly with you finger. Remove jars from dish; cool cakes in jars.
Meanwhile, make raspberry sauce*
Beat cream in a small bowl with electric mixer until soft peaks form.
Top cooled cakes evenly with raspberry sauce, cream, peach slices and almonds.
*Raspberry Sauce: Stir raspberries and Natvia in a small saucepan over low heat for 2 minutes or until Natvia dissolves. Increase heat to medium; cook, stirring, for 2 minutes or until raspberries start to break down and sauce thickens. Cover; refrigerate for 30 minutes or until cold.