Mash the bananas with a fork, then add the vanilla paste, oat milk, oil and oats. Set aside for 10 minutes, then add the flour, baking powder, cinnamon and sugar. Combine well, then fold in the walnuts and raisons.
Preheat the oven to 160°C. Line a loaf tin with parchment paper or paper basket.
Transfer the batter into the tin, spreading it out evenly.
Bake the cake in the middle of the oven for approx. 60 minutes until golden and an inserted skewer comes out clean.
Let it cool in the tin for 5 minutes, then transfer it to a wire rack to cool completely.