Whip the Cream: In a large bowl, pour in the heavy cream. Use an electric mixer (handheld or stand mixer) to whip the cream until soft peaks form.
Sweeten the Cream: Add the powdered sugar and vanilla extract to the whipped cream. Gently mix until stiff peaks form. Be careful not to over-whip.
Prepare the Peach Mixture: In a medium saucepan, combine the sliced peaches, peach preserves, and water.
Cook the Peaches: Place the saucepan over medium heat. Cook, stirring occasionally, until the peaches are slightly softened, about 5-7 minutes.
Cool the Peach Mixture: Remove the peach mixture from the heat and let it cool slightly.
Assemble the Eton Mess: In a large serving bowl or individual glasses, layer the whipped cream, broken meringue pieces, and cooled peach mixture. Repeat the layers until all ingredients are used.
Chill (Optional): If desired, cover and chill in the refrigerator for at least 30 minutes before serving.