Brownie: Position a rack one-third up from the bottom of the oven and preheat
the oven to 350 degrees F. Butter a 9-inch square baking pan and set aside.
Place flour, baking powder, salt and, if desired, cinnamon in a bowl and
stir with a whisk to combine; reserve.
Melt chocolate and butter together in the top of a double boiler over hot
water or in a bowl in the microwave. When melted, stir to blend.
Add the sugar
and mix well, using a small whisk (it is not necessary to pour the chocolate
mixture into a bowl).
Add vanilla extract and eggs, one at a time, stirring
after each addition until the mixture is smooth. After the eggs are added, the
chocolate may look grainy, but it will smooth as you stir it.
Blend in reserved dry ingredients. Set aside while you prepare the cheesecake.
Cheesecake: Dissolve espresso powder in boiling water. Set aside to cool.
Beat cream cheese in a mixer, with a paddle if available, until it is very
Add sugar and vanilla extract and beat until the sugar dissolves, about
Blend in the espresso.
Beat in the eggs one at a time. Beat at medium speed
for 1 minute.
On low speed, add the flour and beat just until blended.
The brownie batter will have thickened a bit while sitting, so give it a
turn with a rubber spatula.
Pour three-quarters of the batter into the prepared
pan, spreading it evenly with the spatula.
Pour over all of the cheesecake batter;
it will spread by itself.
Scatter teaspoonsful of the remaining brownie batter
over the cheesecake. Create a swirl pattern by dipping a table knife halfway
into the batters and drawing it back and forth across the pan. Don't disturb
the bottom layer and don't go across the pan more than once.
Bake for 30 to 35 minutes, until the top is lightly browned and the cake
starts to pull away from the sides of the pan.
Remove from the oven and cool on a rack for 10 minutes.
When the brownies reach room temperature, cover and place in the refrigerator