Preheat an oven to 170 degrees C and prepare an 18cm diameter cake tin.
In a large mixing bowl combine the plain flour, baking powder, brown sugar and caster sugar.
In a separate bowl combine the eggs, vegetable oil, milk and vanilla.
Make a well in the centre of the dry ingredients and tip in the wet ingredients. Quickly and determinedly fold the two mixtures into one lumpy batter trying not to overwork the mixture.
Tip in your blueberries and give one last stir before pouring into the greased cake tin. If you like the blueberries to bleed into the mixture half them or squish a few.
Create the crusty top by scattering over the slivered almonds and a good sprinkling of demerara sugar.
Place in the oven for about 45 minutes until a skewer comes out clean without wet batter sticking to it. If your cake starts to brown a lot on top lower the temperature of the oven a little or cover with foil.
Make this cake into 12 muffins by dividing the mixture equally between 12 muffin cases and cooking at 180 degrees for 25 minutes.