Add all the dry ingredients, namely flour, baking powder, salt, sugar, and lemon zest, to a large bowl. Whisk them together so all the ingredients are equally distributed.
Mix wet ingredients, namely lemon juice, yogurt, melted oil, and milk, into a separate bowl and mix well. You'll add them to the dry ingredients at the end, just before baking.
Warm up oat milk and bring it to boil. While milk is warming up, add poppy seeds and sugar to a bowl and whisk them well. Then pour hot milk over poppy seeds and mix well so there are no dry chunks left.
Now add wet ingredients to dry ingredients and gently mix them, so there are no dry chunks left and you get a homogenous batter.
Grease your baking tin for bundt cakes. Add half of the batter to the bundt cake tin, then add poppy seed filling, and cover with the other half of batter.
Bake for about 50 minutes at 180°C.
Once the cake is baked, let it cool in the tin for a while, then overturn it onto a cooling rack and let it cool down completely.
If you want, you can make lemon icing for the cake and decorate it with icing and poppy seeds.
