Prepare the jam first. Place the raspberries (fresh or frozen) into a saucepan over medium heat. Add in 2 tablespoons lemon juice and 1/4 cup erythritol and bring to a simmer.
Let the jam simmer on medium-high heat for 10 minutes to reduce its liquid. Occasionally stir to ensure the bottom doesn’t catch and burn. Reduce the heat then add in the chia seeds and mix through. Remove from the heat and leave to cool. The chia seeds will also help to thicken the jam.
Preheat the oven to 350F/ 180C. Line a shallow baking tray with baking paper. Separate the eggs. Put the yolks into a large bowl and the whites into a small bowl. Pour the almond milk and avocado oil in with the egg yolks. Whisk to a smooth consistency, then add in the almond flour, psyllium husk, bicarbonate soda and salt. Mix to combine.
Add the egg whites to the bowl of a stand mixer with the whisk attachment. Whisk on medium speed for 1 minute until the eggs start to froth. Add in the remaining 1 teaspoon lemon juice, vanilla extract and erythritol and keep whisking until stiff peaks form, about 5-8 minutes on level 6 speed.
Fold the egg whites into the egg yolk mixture in small batches until a smooth consistency is achieved. Folding is important to keep the air in the mixture.
Pour the batter into the prepared baking tray. Use a spatula to evenly spread the mixture about 1-inch thick. Bake in the middle of the oven for 12-15 minutes or until evenly golden brown.
Remove from the oven and let cool for 15-20 minutes. Evenly spread the raspberry chia jam over the sponge using a spatula. Leave a small border on either end.
Use the baking paper as a guide to roll the sponge over itself starting from the short edge. Carefully and slowly peel the baking paper away as you roll. Serve with your favourite Keto custard or thick pouring cream.