Prepare the Biscuit Base: Place the digestive biscuits into a freezer bag and bash them with a rolling pin until they resemble fine crumbs, like coarse sand. Alternatively, blitz them in a food processor for a quicker, more uniform result. Melt the butter gently in a small saucepan over a low heat until it's a clear, golden liquid, or in the microwave. Pour the melted butter over the biscuit crumbs in a bowl and stir well until every crumb is coated and glistening. The mixture should clump together when pressed.

Layer the Base: Divide the biscuit mixture evenly among 6-8 small jars (about 200ml capacity each). Use the back of a spoon or a small pestle to press the crumbs down firmly into an even layer at the bottom of each jar. You'll notice the crumbs compacting and becoming darker in colour as you press. Place the jars in the fridge to chill while you prepare the filling.

Whip the Cream Cheese Mixture: In a large mixing bowl, beat the softened cream cheese with the sifted icing sugar and vanilla extract using a stand mixer or a hand mixer on medium speed. Continue mixing until the mixture is completely smooth and pale, with no visible lumps, and has a light, airy texture. Scrape down the sides of the bowl to ensure everything is incorporated.

Whip the Double Cream: In a separate, clean bowl, pour in the double cream. Whisk the cream on medium-high speed until it forms soft peaks, meaning it holds its shape but the tips curl over gently. Be careful not to over-whisk, as it can quickly turn grainy. The cream will smell subtly sweet and milky.

Combine and Fill: Gently fold the whipped cream into the cream cheese mixture using a spatula. Use a light hand to maintain the airiness of the cream. Continue folding until just combined and streak-free, creating a thick, creamy, pale ivory mixture. Spoon or pipe the cheesecake filling into the prepared jars, filling them almost to the top. The filling should look perfectly smooth and inviting.

Prepare the Raspberry Sauce: In a small saucepan, combine the raspberries (fresh or frozen), caster sugar, and lemon juice. Heat over a medium heat, stirring occasionally, until the raspberries break down and the sugar dissolves. This usually takes about 5-7 minutes. The mixture will turn a vibrant, deep crimson colour and you'll hear it gently bubbling. If you prefer a smooth sauce, press it through a fine-mesh sieve to remove the seeds. Allow the sauce to cool completely until it's no longer steaming and has thickened slightly.

Assemble and Chill: Once the raspberry sauce is cool, spoon a generous dollop over the cheesecake filling in each jar. You can swirl it gently with a skewer for a marbled effect if you like, or leave it as a distinct layer. Cover the jars and refrigerate for at least 2-4 hours, or ideally overnight, to allow the cheesecake to set properly. When fully chilled, the cheesecake will be firm to the touch and the sauce slightly gelled.