Infuse the Milk: Heat 180 ml whole milk in a small saucepan until just simmering. Remove from heat, stir in 3 tbsp loose Earl Grey tea, cover, and steep for 20 minutes. Strain through a fine sieve, pressing the leaves to extract all the aromatic liquid. Measure out 120 ml and let it cool completely to room temperature.

Make the Blackberry Compote: Combine blackberries, 40 g caster sugar, and lemon juice in a saucepan over medium heat. Simmer for 6–8 minutes until berries burst and soften. Stir in the cornflour slurry and boil gently for 1 minute until thickened and glossy. Transfer to a bowl and chill in the fridge until cold and set.

Prep Tins and Dry Ingredients: Preheat your oven to 175°C (155°C fan / Gas 3–4). Grease and line the bases and sides of two 20 cm (8-inch) round cake tins with baking parchment. In a bowl, whisk together the flour, baking powder, bicarb, salt, and finely ground dry Earl Grey tea leaves.

Mix the Batter: Beat the softened butter and 200 g caster sugar with a stand mixer or hand beaters for 4–5 minutes until pale and aerated. Add eggs one at a time, beating well after each addition along with the vanilla paste. Whisk the sour cream into your 120 ml cooled Earl Grey milk. Alternately fold the dry ingredients (in 3 additions) and the wet milk mixture (in 2 additions) into the creamed butter, mixing only until just combined.

Bake and Soak: Divide batter evenly between tins and smooth the tops. Bake for 24–28 minutes until golden and a skewer inserted in the center comes out clean. While baking, simmer 60 ml brewed Earl Grey with 50 g sugar and lemon juice until dissolved. As soon as cakes leave the oven, prick the tops all over with a skewer and brush the warm syrup generously over both sponges. Let cool in tins for 15 minutes, then turn onto wire racks to cool completely.

Whip the Frosting: In a chilled mixing bowl, combine chilled mascarpone, double cream, icing sugar, honey, and vanilla. Whip on medium-low speed until smooth, thick, and holds medium-stiff peaks.

Assemble the Cake: Place the first sponge layer on a serving plate. Pipe or spread a ring of mascarpone frosting around the top edge to create a dam, then fill the center with the chilled blackberry compote and a thin layer of cream. Top with the second sponge layer. Frost the top and sides with the remaining mascarpone cream. Decorate with fresh blackberries and a light dusting of crushed Earl Grey tea leaves. Chill for 30 minutes before slicing for clean layers.