Preheat the oven to 350°F (175°C). Grease three 8-inch cake pans and line the bottoms with parchment paper.

In a medium bowl, whisk together the gluten-free flour, cocoa powder, baking powder, baking soda, salt, and gum (if using). Set aside.

In the bowl of a stand mixer, combine granulated sugar, brown sugar, eggs, milk, sour cream, avocado oil, apple cider vinegar, and vanilla extract. Beat on medium speed until smooth and well combined.

With the mixer on low, gradually add the dry ingredients to the wet mixture. Scrape the bowl as needed to ensure it’s all incorporated.

Slowly stream in the hot coffee while the mixer is on low. Mix until the batter is smooth (batter will be thin).

Evenly divide the cake batter among the three prepared cake tins. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean (start checking at 20 minutes).

Allow cakes to cool in the pans for 10 minutes before turning out onto a wire rack. Let them cool completely on the cooling rack. For best assembly, wrap and chill the cake layers in the refrigerator for at least 1 hour.

In the bowl of a stand mixer fitted with the paddle attachment, combine the softened butter and creamy peanut butter. Beat on medium-high speed for about 2 minutes, until the mixture is smooth, uniform, and slightly lighter in color. This step ensures a creamy base and eliminates any graininess from the peanut butter.

Reduce the mixer speed to low and slowly add the sifted powdered sugar, about ½ cup at a time. Let each addition incorporate fully before adding the next to prevent a sugar cloud and to ensure a smooth texture. Scrape down the sides and bottom of the bowl frequently to make sure all ingredients are well blended.

Add the vanilla extract and 1 tablespoon of heavy cream. This loosens the frosting slightly and enhances flavor. Increase the mixer speed to medium and beat for a full 5 minutes for the fluffiest frosting. This long whip time introduces air, making the buttercream ultra fluffy and easy to spread or pipe.

If the buttercream feels too thick or stiff, add the second tablespoon of heavy cream a teaspoon at a time until the desired consistency is reached. For piping, you may want it slightly stiffer; for spreading, a softer texture is ideal.

Heat the heavy cream in a saucepan over medium-low heat until it just begins to steam (do not boil), or microwave in 20-second intervals until hot.

Pour the hot cream over the chocolate chips in a heat-safe bowl. Let sit undisturbed for 3–5 minutes.

Stir until smooth and glossy. Let cool to room temperature before using.

Place a small dab of buttercream on the center of a cake board or plate to anchor the cake. Place the first cake layer on top.

Spread a generous layer of creamy peanut butter frosting over the first layer. Optionally, sprinkle on mini chocolate chips or crushed gluten-free chocolate cookies for texture.

Add the second cake layer, more buttercream, and texture toppings if desired.

Place the third cake layer upside down so the flat side faces up. This helps create a sharp, level top.

Apply a thin layer of buttercream over the entire cake. Chill in the freezer for 10–15 minutes to set.

Apply the remaining buttercream and smooth using an offset spatula or cake scraper. You can go for a smooth, clean finish or a rustic swirled design.

Transfer the cooled ganache to a squeeze bottle, piping bag, or plastic bag with the tip cut off. Carefully drip ganache around the top of the cake edges, then fill in the center and gently spread.