Preheat oven to 350° and lightly grease a 4" x 8" loaf pan.
In a small dish, combine chia seeds and water and set aside for 5-10 minutes to gel. This will be your chia "egg".
In another dish or measuring cup, combine 2/3 cup plant milk with 1 tbsp of lemon juice and set aside. Hot tip: always zest your lemons before juicing them so that you're not trying to work with a squished lemon rind.
In a large bowl, whisk together the flour, baking powder, baking soda, poppyseeds and salt.
In another bowl, add the sugar and softened butter and cream together using an electric beat for 2 minutes.
Once the butter and sugar are fluffy, add the vanilla and mix again. Then add the other two tablespoons of lemon juice and the milk mixture to the bowl and beat again.
Pour the chia "egg" and zest into the wet mix and beat for a few seconds to combine. Then add 1/3 of the dry ingredients to the wet and beat, adding the rest of the dry ingredients as they get incorporated until the wet and dry are fully combined. Pour the batter into the greased loaf pan, scrapping the bowl with a spatula to get it all out.
Bake for 50-60 minutes or until a toothpick inserted comes out dry. Let sit for five minutes in the baking dish before transferring to a cooling rack to cool completely.
While the loaf is cooling, prepare the icing by adding the lemon juice and plant milk to the icing sugar and whisking together until smooth.
Once the loaf has cooled, pour or drizzle the icing over the loaf and serve.
