Delightfully airy and irresistibly sweet, Seafoam Squares are a homemade twist on classic marshmallows that will elevate your dessert game. These melt-in-your-mouth confections boast a glossy, cloud-like texture achieved by whipping together fluffy egg whites, a molten sugar syrup, and bloomed gelatin. Infused with fragrant vanilla extract, each square is dusted with a light coating of powdered sugar and cornstarch to create a perfectly soft yet non-sticky treat. Whether enjoyed solo as a sweet snack, paired with hot chocolate, or used to top your favorite desserts, these DIY marshmallows are a versatile delight. With a quick preparation time and just a handful of pantry staples, making Seafoam Squares from scratch is the ultimate way to impress your friends and family with a nostalgic, handmade indulgence.
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Prepare a 9-inch square pan by lightly spraying it with cooking spray. Mix powdered sugar and cornstarch in a small bowl, then generously dust the pan with this mixture, ensuring all sides are coated. Tap out the excess and set aside.
In a small bowl, combine gelatin powder with 1/4 cup cold water. Let it bloom (absorb the water) for 5 minutes while you prepare the syrup and whip the egg whites.
In a medium saucepan, combine granulated sugar, light corn syrup, and 1 cup water. Cook over medium heat, stirring occasionally, until the sugar dissolves. Increase heat to high and bring the mixture to a boil without stirring. Use a candy thermometer and heat until the mixture reaches 240°F (soft-ball stage). Remove from heat.
While the syrup is heating, whip egg whites in a stand mixer fitted with a whisk attachment. Beat on medium-high speed until soft peaks form.
Once the syrup reaches 240°F, slowly pour it into the whipped egg whites in a thin, steady stream while the mixer is running on medium-high speed. Be careful to avoid splashing hot syrup.
Immediately melt the bloomed gelatin in the microwave for about 10 seconds or until liquefied. Pour the liquefied gelatin into the egg white mixture while continuing to beat.
Add vanilla extract and increase the mixer speed to high. Beat the mixture for 6–8 minutes or until stiff peaks form and it has doubled in volume. It should look glossy and fluffy.
Quickly transfer the marshmallow mixture into the prepared pan, smoothing the top with a greased spatula. Work quickly, as the mixture starts to set rapidly.
Let the mixture sit uncovered at room temperature for at least 4 hours (or overnight) to firm up.
Once set, dust a clean work surface with the remaining powdered sugar-cornstarch mixture. Remove the marshmallow block from the pan and place it on the work surface.
Using a sharp knife or scissors coated with nonstick spray, cut the marshmallow block into 16 squares (or any desired size). Roll the sides of each square in the powdered sugar-cornstarch mixture to prevent sticking.
Store the Seafoam Squares in an airtight container at room temperature for up to one week. Enjoy!
Serving size | (843.5g) |
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Amount per serving | % Daily Value* |
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Calories | 1693.4 |
Total Fat 0.2g | 0% |
Saturated Fat 0.0g | 0% |
Polyunsaturated Fat 0g | |
Cholesterol 0mg | 0% |
Sodium 199.2mg | 0% |
Total Carbohydrate 419.5g | 0% |
Dietary Fiber 0.1g | 0% |
Total Sugars 402.1g | |
Protein 17.3g | 0% |
Vitamin D 0IU | 0% |
Calcium 25.3mg | 0% |
Iron 0.2mg | 0% |
Potassium 172.0mg | 0% |
Source of Calories