Choc-Cheese Brownies Slice

I want to experiment different type of cake, brownie.

Ingredients:
185g dark chocolate, chopped
45g butter
2 large eggs
3/4 cup castor sugar (fine sugar)
1/2 cup plain flour
1/4 cup self-raising flour
few drops almond essence
1/2 cup chopped walnuts

Filling:
60g butter
1 teaspoon vanilla essence
185g ricotta cheese
1/4 cup castor sugar
2 large eggs
2 tablespoons plain flour

Procedure:

1. Grease a 19 cm x 29 cm lamington pan.
2. Melt chocolate and butter over hot water, cool; do not allow to set.
3. Beat eggs in small bowl with electric mixer until thick, add sugar gradually, beat until sugar is dissolved.
4. Transfer mixture to large bowl, stir in sifted flours, essence and chocolate mixture.
5. Spread half the chocolate mixture into prepared pan.
6. Top with filling, then remaining chocolate mixture.
7. Run a knife in a zig-zag pattern through mixture, sprinkle evenly with walnuts.
8. Bake in 350 degrees Fahrenheit for about 30 minutes or insert a toothpick into the center of the cake till come out clean.  Cool in pan before cutting. 
9. Store in refrigerator until set.

Filling

1. Beat butter, essence and cheese together in small bowl with electric mixer until mixture is creamy.
2. Add sugar, beat until fluffy, add eggs one at a time, beat until combined.
3. Stir in sifted flour.

Keeping time: 4 days