Dry roast almonds until almonds change it's colour and becomes fragrant. Let it cool down.
Blend or grind the almonds with sugar and orange cookies.
Take out the mixture in a bowl. Mix orange zest and butter in it. Mix everything well.
Grease a baking pan and dust with flour.
Spread the almond mixture on the bottom of the pan and wall too. Press with your fingers to set well. Keep the pan aside.
Preheat the oven at 180° for 10 minutes.
Mix vinegar in lukewarm milk and keep aside.
In a bowl sift together flour, baking powder, soda and cocoa powder.
In a large bowl whisk together oil and sugar. Add vinegar mixed milk in the oil sugar mixture. Whisk again.
Add vanilla essence. Mix well. Then gradually mix the dry ingredients. Mix everything and make a smooth lump free batter.
Now pour the mixture into the greased cake pan. Bake for 30 - 40 minutes or till the toothpick comes out clean. Check after 30 minutes. Every oven takes different time.
Take out the cake when slightly warm. Place on a plate upside down.
Let it cool down completely.
In the meantime prepare the glaze. In a bowl mix 1/2 cup powdered sugar, orange zest, orange food colour and orange juice. Beat well until smooth.
Pour the mixture over upside down cake.
Garnish with orange slices and choco chips.