That is because we allow them to.
As usual our build up play is far too slow.
Too many passes across the back, and midfield, allows teams to defend much easier against us.
It is time for Conte to change to a 4-3-3 formation, to get the ball forward quicker and to also have players running in front of the ball to create space.
I would like us to try this Team when we play them in the 2nd Leg :

Courtois

Zappacosta
Christensen
Luiz
Azpilicueta

Kante
Drinkwater
Barkley

Hazard
Morata
Batshuayi