In a medium saucepan over medium heat, combine fresh or frozen raspberries, granulated sugar, cornstarch, and a splash of lemon juice. Bring the mixture to a boil, stirring constantly for about 5 minutes. Once boiling, reduce the heat and let it simmer for another 5-10 minutes until it thickens. Remove from heat, allowing it to cool while you prepare the dough.

In a large mixing bowl, whisk together all-purpose flour, warm dairy-free milk, vegan butter, sugar, instant dry yeast, ground cinnamon, and salt. Mix until a sticky dough begins to form, then knead on a lightly floured surface for 5-10 minutes until smooth and elastic. The dough should feel soft and stretchy, ready to rise.

Transfer the kneaded dough into a greased bowl, cover it with a damp cloth or plastic wrap, and let it rise in a warm, draft-free place for at least 1 hour. You’ll know it's ready when it has doubled in size and feels airy to the touch.

Once the dough has risen, punch it down to release the air, then roll it out into a rectangle on a floured surface. Spread your cooled raspberry jam evenly over the surface, then carefully roll the dough into a log from one long side to the other. Cut the log in half lengthwise, twist the two halves together, and place the twisted dough into a lined loaf tin. Cover and let it rise again for 1 hour.

Preheat your oven to 170°C (340°F). Gently place the loaf tin in the oven and bake the Jam Donut Babka for 30-40 minutes, or until it is golden brown on top. If it starts to brown too quickly, cover it with foil for the last 10-15 minutes to prevent burning.

While the babka is baking, prepare a simple glaze by heating granulated sugar and water in a small saucepan over low heat. Stir until the sugar has completely dissolved, then set aside. Once the babka is fresh from the oven, drizzle the warm glaze over the top for a sweet finish.

After baking, allow the babka to cool in the tin for about 10 minutes before transferring it to a wire rack. This fluffy Jam Donut Babka is best enjoyed fresh, but can be stored in an airtight container for up to 1-2 days.